@article {4176, title = {7th Operant Conditioning Meeting, Charleston, SC}, year = {2018}, month = {03/2018}, author = {Jonathan Wolpaw} } @article {4143, title = {Acquisition, maintenance, and therapeutic use of a simple motor skill}, journal = {Current Opinion in Behavioral Sciences}, volume = {20}, year = {2018}, pages = {138 - 144}, abstract = {Operant conditioning of the spinal stretch reflex (SSR) or its electrical analog, the H-reflex, is a valuable experimental paradigm for studying the acquisition and maintenance of a simple motor skill. The central nervous system (CNS) substrate of this skill consists of brain and spinal cord plasticity that operates as a hierarchy{\textemdash}the learning experience induces plasticity in the brain that guides and maintains plasticity in the spinal cord. This is apparent in the two components of the skill acquisition: task-dependent adaptation, reflecting brain plasticity; and long-term change, reflecting gradual development of spinal plasticity. The inferior olive, cerebellum, sensorimotor cortex, and corticospinal tract (CST) are essential components of this hierarchy. The neuronal and synaptic mechanisms of the spinal plasticity are under study. Because acquisition of this skill changes the spinal cord, it can affect other skills, such as locomotion. Thus, it enables investigation of how the highly plastic spinal cord supports the acquisition and maintenance of a broad repertoire of motor skills throughout life. These studies have resulted in the negotiated equilibrium model of spinal cord function, which reconciles the spinal cord{\textquoteright}s long-recognized reliability as the final common pathway for behaviors with its recently recognized ongoing plasticity. In accord with this model, appropriate H-reflex conditioning in a person with spasticity due to an incomplete spinal cord injury can trigger wider beneficial plasticity that markedly improves walking. H-reflex operant conditioning appears to provide a valuable new method for enhancing functional recovery in people with spinal cord injury and possibly other disorders as well.}, issn = {2352-1546}, doi = {https://doi.org/10.1016/j.cobeha.2017.12.021}, url = {http://www.sciencedirect.com/science/article/pii/S235215461730219X}, author = {James JS Norton and Jonathan Wolpaw} } @article {4166, title = {Brain-Computer Interfaces For Communication And Control}, year = {2018}, month = {08/2018}, abstract = {NANS Summer Series, New York City, NY}, author = {Jonathan Wolpaw} } @proceedings {4227, title = {Combining H-reflex conditioning and locomotor training appears to enhance locomotor recovery in rats with incomplete spinal cord injury: Initial results}, year = {2018}, month = {11/2018}, author = {X. Y. Chen and L. Chen and X. Yang and Y. Wang and Y. Chen and Jonathan Wolpaw} } @article {4111, title = {Controlling pre-movement sensorimotor rhythm can improve finger extension after stroke}, journal = {Journal of Neural Engineering}, volume = {15}, year = {2018}, month = {08/2018}, abstract = {Objective. Brain{\textendash}computer interface (BCI) technology is attracting increasing interest as a tool for enhancing recovery of motor function after stroke, yet the optimal way to apply this technology is unknown. Here, we studied the immediate and therapeutic effects of BCI-based training to control pre-movement sensorimotor rhythm (SMR) amplitude on robot-assisted finger extension in people with stroke. Approach. Eight people with moderate to severe hand impairment due to chronic stroke completed a four-week three-phase protocol during which they practiced finger extension with assistance from the FINGER robotic exoskeleton. In Phase 1, we identified spatiospectral SMR features for each person that correlated with the intent to extend the index and/or middle finger(s). In Phase 2, the participants learned to increase or decrease SMR features given visual feedback, without movement. In Phase 3, the participants were cued to increase or decrease their SMR features, and when successful, were then cued to immediately attempt to extend the finger(s) with robot assistance. Main results. Of the four participants that achieved SMR control in Phase 2, three initiated finger extensions with a reduced reaction time after decreasing (versus increasing) pre-movement SMR amplitude during Phase 3. Two also extended at least one of their fingers more forcefully after decreasing pre-movement SMR amplitude. Hand function, measured by the box and block test (BBT), improved by 7.3 {\textpm} 7.5 blocks versus 3.5 {\textpm} 3.1 blocks in those with and without SMR control, respectively. Higher BBT scores at baseline correlated with a larger change in BBT score. Significance. These results suggest that learning to control person-specific pre-movement SMR features associated with finger extension can improve finger extension ability after stroke for some individuals. These results merit further investigation in a rehabilitation context.}, keywords = {BCI, Motor control, Rehabilitation, robot, sensorimotor rhythm, Stroke}, doi = {10.1088/1741-2552/aad724}, url = {http://stacks.iop.org/1741-2552/15/i=5/a=056026}, author = {Norman, SL and McFarland, DJ and Miner, A and Cramer, SC and Wolbrecht, ET and Jonathan Wolpaw and Reinkensmeyer, DJ} } @proceedings {4170, title = {Creating an eyes-closed binary SSVEP-based brain-computer interface (BCI) for the bedside: A comparison of foveal centered and off-centered stimulus presentation}, year = {2018}, month = {11/2018}, address = {San Diego, CA}, author = {T.M. Vaughan and M. Aslam and B. Zoltan and Peter Brunner and J. J. Norton and C. S. Carmack and D. J. Zeitlin and Jonathan Wolpaw} } @proceedings {4225, title = {Creating an eyes-closed binary SSVEP-based brain-computer interface (BCI) for the bedside: A comparison of foveal centered and off-centered stimulus presentation}, year = {2018}, month = {11/2018}, author = {T. M. Vaughan and M. Aslam and B. Zoltan and Peter Brunner and J. J. Norton and C. S. Carmack and D. J. Zeitlin and Jonathan Wolpaw} } @article {4164, title = {Department of Kinesiology, Penn State University, State College, PA.}, year = {2018}, month = {10/2018}, author = {Jonathan Wolpaw} } @article {4110, title = {Effects of Sensorimotor Rhythm Modulation on the Human Flexor Carpi Radialis H-Reflex}, journal = {Frontiers in Neuroscience}, volume = {12}, year = {2018}, month = {07/2018}, chapter = {505}, abstract = {People can learn over training sessions to increase or decrease sensorimotor rhythms (SMRs) in the electroencephalogram (EEG). Activity-dependent brain plasticity is thought to guide spinal plasticity during motor skill learning; thus, SMR training may affect spinal reflexes and thereby influence motor control. To test this hypothesis, we investigated the effects of learned mu (8{\textendash}13 Hz) SMR modulation on the flexor carpi radialis (FCR) H-reflex in 6 subjects with no known neurological conditions and 2 subjects with chronic incomplete spinal cord injury (SCI). All subjects had learned and practiced over more than 10 < 30-min training sessions to increase (SMR-up trials) and decrease (SMR-down trials) mu-rhythm amplitude over the hand/arm area of left sensorimotor cortex with >=80\% accuracy. Right FCR H-reflexes were elicited at random times during SMR-up and SMR-down trials, and in between trials. SMR modulation affected H-reflex size. In all the neurologically normal subjects, the H-reflex was significantly larger [116\% {\textpm} 6 (mean {\textpm} SE)] during SMR-up trials than between trials, and significantly smaller (92\% {\textpm} 1) during SMR-down trials than between trials (p < 0.05 for both, paired t-test). One subject with SCI showed similar H-reflex size dependence (high for SMR-up trials, low for SMR-down trials): the other subject with SCI showed no dependence. These results support the hypothesis that SMR modulation has predictable effects on spinal reflex excitability in people who are neurologically normal; they also suggest that it might be used to enhance therapies that seek to improve functional recovery in some individuals with SCI or other CNS disorders. }, keywords = {brain-computer interface (BC), EEG mu-rhythm, H-Reflex, Spinal Cord Injuries, task-dependent adaptation}, issn = {1662-453X}, doi = {10.3389/fnins.2018.00505}, url = {https://www.frontiersin.org/article/10.3389/fnins.2018.00505}, author = {Thompson, AK and Carruth, H and Haywood, R and Hill, NJ and Sarnacki, WA and McCane, LM and Jonathan Wolpaw and McFarland, DJ} } @article {4109, title = {Independent home use of a brain-computer interface by people with amyotrophic lateral sclerosis}, journal = {Neurology}, year = {2018}, month = {06/2018}, abstract = {Objective: To assess the reliability and usefulness of an EEG-based brain-computer interface (BCI) for patients with advanced amyotrophic lateral sclerosis (ALS) who used it independently at home for up to 18 months. Methods: Of 42 patients consented, 39 (93\%) met the study criteria, and 37 (88\%) were assessed for use of the Wadsworth BCI. Nine (21\%) could not use the BCI. Of the other 28, 27 (men, age 28{\textendash}79 years) (64\%) had the BCI placed in their homes, and they and their caregivers were trained to use it. Use data were collected by Internet. Periodic visits evaluated BCI benefit and burden and quality of life. Results: Over subsequent months, 12 (29\% of the original 42) left the study because of death or rapid disease progression and 6 (14\%) left because of decreased interest. Fourteen (33\%) completed training and used the BCI independently, mainly for communication. Technical problems were rare. Patient and caregiver ratings indicated that BCI benefit exceeded burden. Quality of life remained stable. Of those not lost to the disease, half completed the study; all but 1 patient kept the BCI for further use. Conclusion: The Wadsworth BCI home system can function reliably and usefully when operated by patients in their homes. BCIs that support communication are at present most suitable for people who are severely disabled but are otherwise in stable health. Improvements in BCI convenience and performance, including some now underway, should increase the number of people who find them useful and the extent to which they are used.}, keywords = {All clinical neurophysiology, All Neuromuscular Disease, Evoked Potentials, visual}, issn = {1526-632X}, doi = {https://doi.org/10.1212/WNL.0000000000005812}, url = {http://n.neurology.org/content/neurology/early/2018/06/27/WNL.0000000000005812.full.pdf}, author = {Jonathan Wolpaw and Bedlack, RS and Reda, DJ and Ringer, RJ and Banks, PG and Vaughan, TM and Heckman, SM and McCrane, LM and Carmack, CS and Winden, S and McFarland, DJ and Sellers, EW and Shi, H and Paine, T and Higgins, DS and Lo, AC and Patwa, HS and Hill, KJ and Huang, GS and Ruff, RL} } @article {4175, title = {McDowell Award Lecture}, year = {2018}, month = {05/2018}, abstract = {Burke Neurological Research Inst, Weill-Cornell Sch Med, White Plains, NY}, author = {Jonathan Wolpaw} } @article {4162, title = {National Center for Neuromodulation for Rehabilitation Workshop, Medical University of South Carolina, Charleston, SC.}, year = {2018}, month = {11/2018}, author = {Jonathan Wolpaw} } @article {4171, title = {Neuromodulation for Rehabilitation after Spinal Cord Injury}, year = {2018}, month = {08/2018}, abstract = {NANS Summer Series, New York City, NY, August, 2018}, author = {Jonathan Wolpaw} } @article {4173, title = {NeuroRehabilitation CME Course, Harvard Medical School, Waltham, MA}, year = {2018}, month = {06/2018}, author = {Jonathan Wolpaw} } @article {4165, title = {New York State Spinal Cord Injury Research Board Symposium, New York, NY.}, year = {2018}, month = {10/2018}, author = {Jonathan Wolpaw} } @article {4174, title = {Organizer and Speaker}, year = {2018}, month = {05/2018}, abstract = {Neuroethics Symposium, Seventh International Brain-Computer Interface Meeting, Asilomar, CA}, author = {Jonathan Wolpaw} } @article {4172, title = {Progress in Clinical Motor Control Symposium, Penn State Univ, State College, PA}, year = {2018}, month = {07/2018}, abstract = { }, author = {Jonathan Wolpaw} } @article {4108, title = {Retraining Reflexes: Clinical Translation of Spinal Reflex Operant Conditioning}, journal = {Neurotherapeutics}, volume = {15}, year = {2018}, month = {07/2018}, pages = {669-683}, abstract = {Neurological disorders, such as spinal cord injury, stroke, traumatic brain injury, cerebral palsy, and multiple sclerosis cause motor impairments that are a huge burden at the individual, family, and societal levels. Spinal reflex abnormalities contribute to these impairments. Spinal reflex measurements play important roles in characterizing and monitoring neurological disorders and their associated motor impairments, such as spasticity, which affects nearly half of those with neurological disorders. Spinal reflexes can also serve as therapeutic targets themselves. Operant conditioning protocols can target beneficial plasticity to key reflex pathways; they can thereby trigger wider plasticity that improves impaired motor skills, such as locomotion. These protocols may complement standard therapies such as locomotor training and enhance functional recovery. This paper reviews the value of spinal reflexes and the therapeutic promise of spinal reflex operant conditioning protocols; it also considers the complex process of translating this promise into clinical reality.}, keywords = {clinical translation, H-Reflex, neurological disorders, operant conditioning, plasticity, Rehabilitation, spinal reflex}, issn = {1878-7479}, doi = {https://doi.org/10.1007/s13311-018-0643-2}, url = {https://link.springer.com/article/10.1007/s13311-018-0643-2}, author = {Eftekhar, A and Norton, JJS and McDonough, CM and Jonathan Wolpaw} } @article {4163, title = {Spinal Cord Plasticity in Motor Control Symposium, San Diego, CA.}, year = {2018}, month = {11/2018}, author = {Jonathan Wolpaw} } @proceedings {4226, title = {Towards operant conditioning of the flexor carpi radialis: Methods and initial results}, year = {2018}, month = {11/2018}, author = {J. Norton and A. Eftekhar and S. Heckman and J. H. Barnes and L. McCane and Jonathan Wolpaw} } @article {4184, title = {Activity-Dependent Plasticity in the CNS}, year = {2017}, month = {07/2017}, abstract = {NIH Short Course in Adaptive Neurotechnologies, Wadsworth Center, Albany, NY}, author = {Jonathan Wolpaw} } @article {4177, title = {Center for Brain Plasticity and Recovery, Georgetown Univ. Med. Ctr., Washington, DC}, year = {2017}, month = {11/2017}, author = {Jonathan Wolpaw} } @article {4186, title = {Demystifying Medicine Lecture}, year = {2017}, month = {04/2017}, abstract = {National Institutes of Health, Bethesda, MD}, author = {Jonathan Wolpaw} } @article {4178, title = {Distinguished Scholar Lecture Series, University of Delaware, Newark, DE}, year = {2017}, month = {11/2017}, author = {Jonathan Wolpaw} } @article {4093, title = {EEG-based brain-computer interfaces}, journal = {Current Opinion in Biomedical Engineering}, volume = {4}, year = {2017}, month = {Oct}, pages = {194-200}, abstract = {Brain{\textendash}Computer Interfaces (BCIs) are real-time computer-based systems that translate brain signals into useful commands. To date most applications have been demonstrations of proof-of-principle; widespread use by people who could benefit from this technology requires further development. Improvements in current EEG recording technology are needed. Better sensors would be easier to apply, more comfortable for the user, and produce higher quality and more stable signals. Although considerable effort has been devoted to evaluating classifiers using public datasets, more attention to real-time signal processing issues and to optimizing the mutually adaptive interaction between the brain and the BCI are essential for improving BCI performance. Further development of applications is also needed, particularly applications of BCI technology to rehabilitation. The design of rehabilitation applications hinges on the nature of BCI control and how it might be used to induce and guide beneficial plasticity in the brain.}, keywords = {brain-computer interface, neurotechnology, Rehabilitation}, issn = {2468-4511}, doi = {doi.org/10.1016/j.cobme.2017.11.004.}, url = {https://www.ncbi.nlm.nih.gov/pubmed/21438193}, author = {McFarland, D. J. and Jonathan Wolpaw} } @article {4187, title = {Invited Speaker}, year = {2017}, month = {04/2017}, abstract = {Department of Rehabilitation Medicine, Emory University School of Medicine, Atlanta, GA}, author = {Jonathan Wolpaw} } @article {4181, title = {National Center of Neuromodulation for Rehabilitation (NM4R) Workshop, Charleston, SC}, year = {2017}, month = {10/2017}, author = {Jonathan Wolpaw} } @article {4185, title = {NeuroRehabilitation CME Course, Harvard Medical School, Waltham, MA}, year = {2017}, month = {06/2017}, author = {Jonathan Wolpaw} } @article {3567, title = {Nothing either good or bad but action makes it so.}, journal = {The Journal of physiology}, volume = {595}, year = {2017}, month = {Feb}, pages = {1003{\textendash}1004}, issn = {1469-7793}, doi = {10.1113/JP273392}, url = {http://www.ncbi.nlm.nih.gov/pubmed/28198019}, author = {Jonathan Wolpaw and Thompson, Aiko K.} } @article {4182, title = {Plenary Lecture, Summer School on Neurorehabilitation, Baiona, Spain}, year = {2017}, month = {09/2017}, author = {Jonathan Wolpaw} } @article {3570, title = {Prediction of subjective ratings of emotional pictures by EEG features.}, journal = {Journal of neural engineering}, volume = {14}, year = {2017}, month = {Feb}, pages = {016009}, abstract = {Emotion dysregulation is an important aspect of many psychiatric disorders. Brain-computer interface (BCI) technology could be a powerful new approach to facilitating therapeutic self-regulation of emotions. One possible BCI method would be to provide stimulus-specific feedback based on subject-specific electroencephalographic (EEG) responses to emotion-eliciting stimuli.}, issn = {1741-2552}, doi = {10.1088/1741-2552/14/1/016009}, url = {http://www.ncbi.nlm.nih.gov/pubmed/27934776}, author = {Dennis J. McFarland and Parvaz, Muhammad A. and Sarnacki, William A. and Goldstein, Rita Z. and Jonathan Wolpaw} } @article {4183, title = {Progress in Motor Control IX, University of Miami, Miami, FL}, year = {2017}, month = {07/2017}, author = {Jonathan Wolpaw} } @article {3568, title = {Spinal transection alters external urethral sphincter activity during spontaneous voiding in freely-moving rats.}, journal = {Journal of neurotrauma}, year = {2017}, month = {May}, abstract = {The rat is a commonly used model for the study of lower urinary tract function before and after spinal cord injury. We have previously reported that in unanesthetized, freely-moving rats, although phasic external urethral sphincter (EUS) activity (bursting) is most common during micturition, productive voiding can occur in the absence of bursting, which differs from results seen in anesthetized or unanesthetized restrained animals. The purpose of the present study was to characterize EUS behavior in unanesthetized, freely-moving rats before and after mid-thoracic (T8) or thoraco-lumbar (T13-L1) spinal transection to determine how EUS behavior after spinal cord injury differs from that seen in anesthetized or unanesthetized restrained rats. Several abnormalities became evident that were comparable after transection at either level including: repetitive non-voiding EUS contractions; increased prevalence, intensity and duration of EUS bursting; decreased rate of urine evacuation during bursting; increased void size and decreased number of daily voids; shorter inter-burst silent period and increased frequency of bursting; and loss of the direct linear relationships that are evident in intact animals between void size and bursting silent period. These data suggest that transection-induced delayed initiation of EUS bursting allows co-contraction of the bladder and the EUS that prevents or limits urine evacuation, resulting in a detrusor-sphincter dyssynergia-like phenomenon. In addition, the higher-than-normal frequency at which EUS bursting occurs after transection is associated with shorter silent periods during which urine typically flows, which interferes with voiding by slowing the rate of urine evacuation. That results were comparable after either transection suggests that the central pattern generator responsible for EUS bursting is located caudal to the L1 spinal segment.}, issn = {1557-9042}, doi = {10.1089/neu.2016.4844}, url = {http://www.ncbi.nlm.nih.gov/pubmed/28467736}, author = {LaPallo, Brandon K. and Jonathan Wolpaw and Xiang Yang Chen and Jonathan S. Carp} } @article {4094, title = {Why New Spinal Cord Plasticity Does Not Disrupt Old Motor Behaviors}, journal = {The Journal of Neuroscience}, volume = {37}, year = {2017}, month = {July}, pages = {8198-8206}, abstract = {When new motor learning changes the spinal cord, old behaviors are not impaired; their key features are preserved by additional compensatory plasticity. To explore the mechanisms responsible for this compensatory plasticity, we transected the spinal dorsal ascending tract before or after female rats acquired a new behavior{\textemdash}operantly conditioned increase or decrease in the right soleus H-reflex{\textemdash}and examined an old behavior{\textemdash}locomotion. Neither spinal dorsal ascending tract transection nor H-reflex conditioning alone impaired locomotion. Nevertheless, when spinal dorsal ascending tract transection and H-reflex conditioning were combined, the rats developed a limp and a tilted posture that correlated in direction and magnitude with the H-reflex change. When the right H-reflex was increased by conditioning, the right step lasted longer than the left and the right hip was higher than the left; when the right H-reflex was decreased by conditioning, the opposite occurred. These results indicate that ascending sensory input guides the compensatory plasticity that normally prevents the plasticity underlying H-reflex change from impairing locomotion. They support the concept of the state of the spinal cord as a negotiated equilibrium that reflects the concurrent influences of all the behaviors in an individual{\textquoteright}s repertoire; and they support the new therapeutic strategies this concept introduces.}, keywords = {H-Reflex, motor learning, operant conditioning, plasticity, Rehabilitation, Spinal Cord}, doi = {10.1523/JNEUROSCI.0767-17.2017}, url = {https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5566867/}, author = {Chen, Yi and Chen, Lu and Wang, Yu and Chen, Xiang Yang and Jonathan Wolpaw} } @article {4196, title = {50th Anniversary Symposium, Spinal Cord Injury Center, Heidelberg University Hospital, Heidelberg, Germany}, year = {2016}, month = {06/2016}, author = {Jonathan Wolpaw} } @article {3565, title = {Ablation of the inferior olive prevents H-reflex down-conditioning in rats.}, journal = {Journal of neurophysiology}, volume = {115}, year = {2016}, month = {Mar}, pages = {1630{\textendash}1636}, abstract = {We evaluated the role of the inferior olive (IO) in acquisition of the spinal cord plasticity that underlies H-reflex down-conditioning, a simple motor skill. The IO was chemically ablated before a 50-day exposure to an operant conditioning protocol that rewarded a smaller soleus H-reflex. In normal rats, down-conditioning succeeds (i.e., H-reflex size decreases at least 20\%) in 80\% of animals. Down-conditioning failed in every IO-ablated rat (P< 0.001 vs. normal rats). IO ablation itself had no long-term effect on H-reflex size. These results indicate that the IO is essential for acquisition of a down-conditioned H-reflex. With previous data, they support the hypothesis that IO and cortical inputs to cerebellum enable the cerebellum to guide sensorimotor cortex plasticity that produces and maintains the spinal cord plasticity that underlies the down-conditioned H-reflex. They help to further define H-reflex conditioning as a model for understanding motor learning and as a new approach to enhancing functional recovery after trauma or disease.}, keywords = {Spinal Cord}, issn = {1522-1598}, doi = {10.1152/jn.01069.2015}, url = {http://www.ncbi.nlm.nih.gov/pubmed/26792888}, author = {Xiang Yang Chen and Wang, Yu and Yi Chen and Chen, Lu and Jonathan Wolpaw} } @article {4193, title = {Activity-Dependent Plasticity in the CNS}, year = {2016}, month = {07/2016}, abstract = {NIH Short Course in Adaptive Neurotechnologies, Wadsworth Center, Albany, NY}, author = {Jonathan Wolpaw} } @article {4198, title = {Atlantic Health Symposium, Atlantic Neuroscience Institute, Overlook Med Center, Summit, NJ}, year = {2016}, month = {04/2016}, author = {Jonathan Wolpaw} } @article {3564, title = {Contribution of the external urethral sphincter to urinary void size in unanesthetized unrestrained rats.}, journal = {Neurourology and urodynamics}, volume = {35}, year = {2016}, month = {Aug}, pages = {696{\textendash}702}, abstract = {In anesthetized rats, voiding is typically associated with phasic activation (bursting) of the external urethral sphincter (EUS). During spontaneous voiding in unanesthetized, unrestrained rats, EUS bursting is the most common form of EUS activity exhibited, but it is not necessary for productive voiding to occur. The aim of the present study was to determine which aspects of EUS activity contributed to void size during bursting and non-bursting voiding in conscious, freely moving rats.}, issn = {1520-6777}, doi = {10.1002/nau.22789}, url = {http://www.ncbi.nlm.nih.gov/pubmed/25995074}, author = {LaPallo, Brandon K. and Jonathan Wolpaw and Xiang Yang Chen and Jonathan S. Carp} } @article {4200, title = {Department of Cognitive Science, Rensselaer Polytechnic Institute, Troy, NY}, year = {2016}, month = {04/2016}, author = {Jonathan Wolpaw} } @article {4202, title = {Departments of Rehabilitation and Biomedical Engineering, Emory University and Georgia Institute of Technology, Atlanta, GA}, year = {2016}, month = {03/2016}, author = {Jonathan Wolpaw} } @article {4201, title = {Grand Rounds, Department of Neurology, Columbia University, New York, NY}, year = {2016}, month = {04/2016}, author = {Jonathan Wolpaw} } @article {3566, title = {The inferior olive is essential for long-term maintenance of a simple motor skill.}, journal = {Journal of neurophysiology}, volume = {116}, year = {2016}, month = {Oct}, pages = {1946{\textendash}1955}, abstract = {The inferior olive (IO) is essential for operant down-conditioning of the rat soleus H-reflex, a simple motor skill. To evaluate the role of the IO in long-term maintenance of this skill, the H-reflex was down-conditioned over 50 days, the IO was chemically ablated, and down-conditioning continued for up to 102 more days. H-reflex size just before IO ablation averaged 62({\textpm}2 SE)\% of its initial value (P < 0.001 vs. initial). After IO ablation, H-reflex size rose to 75-80\% over ?10 days, remained there for ?30 days, rose over 10 days to above its initial value, and averaged 140({\textpm}14)\% for the final 10 days of study (P < 0.01 vs. initial). This two-stage loss of down-conditioning maintenance correlated with IO neuronal loss (r = 0.75, P < 0.01) and was similar to the loss of down-conditioning that follows ablation of the cerebellar output nuclei dentate and interpositus. In control (i.e., unconditioned) rats, IO ablation has no long-term effect on H-reflex size. These results indicate that the IO is essential for long-term maintenance of a down-conditioned H-reflex. With previous data, they support the hypothesis that IO and cortical inputs to cerebellum combine to produce cerebellar plasticity that produces sensorimotor cortex plasticity that produces spinal cord plasticity that produces the smaller H-reflex. H-reflex down-conditioning appears to depend on a hierarchy of plasticity that may be guided by the IO and begin in the cerebellum. Similar hierarchies may underlie other motor learning.}, issn = {1522-1598}, doi = {10.1152/jn.00085.2016}, url = {http://www.ncbi.nlm.nih.gov/pubmed/27535367}, author = {Xiang Yang Chen and Wang, Yu and Yi Chen and Chen, Lu and Jonathan Wolpaw} } @article {4192, title = {Keynote Lecture, Neural Engineering Research Symposium, University of Miami, Miami, FL}, year = {2016}, month = {10/2016}, author = {Jonathan Wolpaw} } @article {4203, title = { Keynote Speaker, Neuromodulation for Rehabilitation Workshop, Medical University of South Carolina, Charleston, SC}, year = {2016}, month = {03/2016}, author = {Jonathan Wolpaw} } @article {4191, title = {The Miami Project, University of Miami, Miami, FL}, year = {2016}, month = {10/2016}, author = {Jonathan Wolpaw} } @article {4190, title = {Neuromodulation for Rehabilitation Workshop, Medical University of South Carolina, Charleston, SC}, year = {2016}, month = {10/2016}, author = {Jonathan Wolpaw} } @article {4199, title = {Pioneer Award Lecture, SPIE Conference, Baltimore, MD}, year = {2016}, month = {04/2016}, author = {Jonathan Wolpaw} } @article {4188, title = {Plenary Lecture, International Conference on Neurorehabilitation, Segovia, Spain}, year = {2016}, month = {10/2016}, author = {Jonathan Wolpaw} } @article {4197, title = {Presidential Lecture, Sixth Annual International Brain-Computer Interface Meeting, Asilomar, CA}, year = {2016}, month = {05/2016}, author = {Jonathan Wolpaw} } @article {4195, title = {Session Chair, Neural Interfaces Conference, Baltimore, MD}, year = {2016}, month = {06/2016}, author = {Jonathan Wolpaw} } @article {4189, title = {Symposium, International Conference on Neurorehabilitation, Segovia, Spain}, year = {2016}, month = {10/2016}, author = {Jonathan Wolpaw} } @article {4194, title = {Symposium, International Society of Electrophysiology and Kinesiology, Chicago, IL}, year = {2016}, month = {07/2016}, author = {Jonathan Wolpaw} } @article {4211, title = {Biomedical Technology Research Centers Principal Investigator Annual Meeting, Rockville, MD}, year = {2015}, month = {03/2015}, author = {Jonathan Wolpaw} } @article {3569, title = {Effects of training pre-movement sensorimotor rhythms on behavioral performance.}, journal = {Journal of neural engineering}, volume = {12}, year = {2015}, month = {Dec}, pages = {066021}, abstract = {Brain-computer interface (BCI) technology might contribute to rehabilitation of motor function. This speculation is based on the premise that modifying the electroencephalographic (EEG) activity will modify behavior, a proposition for which there is limited empirical data. The present study asked whether learned modulation of pre-movement sensorimotor rhythm (SMR) activity can affect motor performance in normal human subjects.}, keywords = {sensorimotor cortex}, issn = {1741-2552}, doi = {10.1088/1741-2560/12/6/066021}, url = {http://www.ncbi.nlm.nih.gov/pubmed/26529119}, author = {Dennis J. McFarland and Sarnacki, William A. and Jonathan Wolpaw} } @article {3382, title = {Electrocorticographic activity over sensorimotor cortex and motor function in awake behaving rats.}, journal = {J Neurophysiol}, volume = {113}, year = {2015}, month = {04/2015}, pages = {2232-41}, abstract = {

Sensorimotor cortex exerts both short-term and long-term control over the spinal reflex pathways that serve motor behaviors. Better understanding of this control could offer new possibilities for restoring function after central nervous system trauma or disease. We examined the impact of ongoing sensorimotor cortex (SMC) activity on the largely monosynaptic pathway of the H-reflex, the electrical analog of the spinal stretch reflex. In 41 awake adult rats, we measured soleus electromyographic (EMG) activity, the soleus H-reflex, and electrocorticographic activity over the contralateral SMC while rats were producing steady-state soleus EMG activity. Principal component analysis of electrocorticographic frequency spectra before H-reflex elicitation consistently revealed three frequency bands: μβ (5-30 Hz), low γ (γ1; 40-85 Hz), and high γ (γ2; 100-200 Hz). Ongoing (i.e., background) soleus EMG amplitude correlated negatively with μβ power and positively with γ1 power. In contrast, H-reflex size correlated positively with μβ power and negatively with γ1 power, but only when background soleus EMG amplitude was included in the linear model. These results support the hypothesis that increased SMC activation (indicated by decrease in μβ power and/or increase in γ1 power) simultaneously potentiates the H-reflex by exciting spinal motoneurons and suppresses it by decreasing the efficacy of the afferent input. They may help guide the development of new rehabilitation methods and of brain-computer interfaces that use SMC activity as a substitute for lost or impaired motor outputs.

}, keywords = {brain-computer interface, cortex, H-Reflex, Motor control, Spinal Cord}, issn = {1522-1598}, doi = {10.1152/jn.00677.2014}, url = {http://www.ncbi.nlm.nih.gov/pubmed/25632076}, author = {Chadwick B. Boulay and Xiang Yang Chen and Jonathan Wolpaw} } @article {4209, title = {How the CNS operates as a multi-user system}, year = {2015}, month = {04/2015}, abstract = {Panel (Chairman), Neural Control of Movement Meeting, Charleston, SC}, author = {Jonathan Wolpaw} } @article {4208, title = {Kavli Seminar, Center for Sensorimotor Neural Engineering, Seattle, WA}, year = {2015}, month = {04/2015}, author = {Jonathan Wolpaw} } @article {4207, title = {Keynote Address, College of Health Sciences Spring Research Symposium, University of Wisconsin, Milwaukee, WI}, year = {2015}, month = {05/2015}, author = {Jonathan Wolpaw} } @article {3381, title = {P300-based brain-computer interface (BCI) event-related potentials (ERPs): People with amyotrophic lateral sclerosis (ALS) vs. age-matched controls.}, journal = {Clin Neurophysiol}, year = {2015}, month = {02/2015}, abstract = {

OBJECTIVE: Brain-computer interfaces (BCIs) aimed at restoring communication to people with severe neuromuscular disabilities often use event-related potentials (ERPs) in scalp-recorded EEG activity. Up to the present, most research and development in this area has been done in the laboratory with young healthy control subjects. In order to facilitate the development of BCI most useful to people with disabilities, the present study set out to: (1) determine whether people with amyotrophic lateral sclerosis (ALS) and healthy, age-matched volunteers (HVs) differ in the speed and accuracy of their ERP-based BCI use; (2) compare the ERP characteristics of these two groups; and (3) identify ERP-related factors that might enable improvement in BCI performance for people with disabilities.

METHODS: Sixteen EEG channels were recorded while people with ALS or healthy age-matched volunteers (HVs) used a P300-based BCI. The subjects with ALS had little or no remaining useful motor control (mean ALS Functional Rating Scale-Revised 9.4 ({\textpm}9.5SD) (range 0-25)). Each subject attended to a target item as the items in a 6{\texttimes}6 visual matrix flashed. The BCI used a stepwise linear discriminant function (SWLDA) to determine the item the user wished to select (i.e., the target item). Offline analyses assessed the latencies, amplitudes, and locations of ERPs to the target and non-target items for people with ALS and age-matched control subjects.

RESULTS: BCI accuracy and communication rate did not differ significantly between ALS users and HVs. Although ERP morphology was similar for the two groups, their target ERPs differed significantly in the location and amplitude of the late positivity (P300), the amplitude of the early negativity (N200), and the latency of the late negativity (LN).

CONCLUSIONS: The differences in target ERP components between people with ALS and age-matched HVs are consistent with the growing recognition that ALS may affect cortical function. The development of BCIs for use by this population may begin with studies in HVs but also needs to include studies in people with ALS. Their differences in ERP components may affect the selection of electrode montages, and might also affect the selection of presentation parameters (e.g., matrix design, stimulation rate).

SIGNIFICANCE: P300-based BCI performance in people severely disabled by ALS is similar to that of age-matched control subjects. At the same time, their ERP components differ to some degree from those of controls. Attention to these differences could contribute to the development of BCIs useful to those with ALS and possibly to others with severe neuromuscular disabilities.

}, keywords = {alternative and augmentative communication (AAC), amyotrophic lateral sclerosis (ALS), Brain-computer interface (BCI), brain-machine interface (BMI), electroencephalography (EEG), event-related potentials (ERP)}, issn = {1872-8952}, doi = {10.1016/j.clinph.2015.01.013}, url = {http://www.ncbi.nlm.nih.gov/pubmed/25703940}, author = {McCane, Lynn M and Susan M Heckman and Dennis J. McFarland and Townsend, George and Mak, Joseph N and Sellers, Eric W and Zeitlin, Debra and Tenteromano, Laura M and Jonathan Wolpaw and Theresa M Vaughan} } @article {3388, title = {Restoring walking after spinal cord injury: operant conditioning of spinal reflexes can help.}, journal = {Neuroscientist}, volume = {21}, year = {2015}, month = {04/2015}, pages = {203-15}, abstract = {

People with incomplete spinal cord injury (SCI) frequently suffer motor disabilities due to spasticity and poor muscle control, even after conventional therapy. Abnormal spinal reflex activity often contributes to these problems. Operant conditioning of spinal reflexes, which can target plasticity to specific reflex pathways, can enhance recovery. In rats in which a right lateral column lesion had weakened right stance and produced an asymmetrical gait, up-conditioning of the right soleus H-reflex, which increased muscle spindle afferent excitation of soleus, strengthened right stance and eliminated the asymmetry. In people with hyperreflexia due to incomplete SCI, down-conditioning of the soleus H-reflex improved walking speed and symmetry. Furthermore, modulation of electromyographic activity during walking improved bilaterally, indicating that a protocol that targets plasticity to a specific pathway can trigger widespread plasticity that improves recovery far beyond that attributable to the change in the targeted pathway. These improvements were apparent to people in their daily lives. They reported walking faster and farther, and noted less spasticity and better balance. Operant conditioning protocols could be developed to modify other spinal reflexes or corticospinal connections; and could be combined with other therapies to enhance recovery in people with SCI or other neuromuscular disorders.

}, keywords = {Learning, Locomotion, spinal cord injury, spinal cord plasticity, spinal reflexes}, issn = {1089-4098}, doi = {10.1177/1073858414527541}, url = {http://www.ncbi.nlm.nih.gov/pubmed/24636954}, author = {Thompson, Aiko K and Jonathan Wolpaw} } @article {4210, title = {Spinal Cord Injury Grand Rounds, Medical University of South Carolina, Charleston, SC}, year = {2015}, month = {04/2015}, author = {Jonathan Wolpaw} } @article {4206, title = {Summer School on Neurorehabilitation, Valencia, Spain}, year = {2015}, month = {09/2015}, author = {Jonathan Wolpaw} } @article {4204, title = {Symposium, American Congress of Rehabilitation Medicine, Dallas, TX}, year = {2015}, month = {10/2015}, author = {Jonathan Wolpaw} } @article {4205, title = {Symposium, Annual Meeting of the Society for Neuroscience, Chicago, IL}, year = {2015}, month = {10/2015}, author = {Jonathan Wolpaw} } @inbook {3380, title = {Targeted neuroplasticity for rehabilitation.}, booktitle = {Progress in Brain Research}, volume = {218}, year = {2015}, month = {03/2015}, pages = {157-72}, abstract = {

An operant-conditioning protocol that bases reward on the electromyographic response produced by a specific CNS pathway can change that pathway. For example, in both animals and people, an operant-conditioning protocol can increase or decrease the spinal stretch reflex or its electrical analog, the H-reflex. Reflex change is associated with plasticity in the pathway of the reflex as well as elsewhere in the spinal cord and brain. Because these pathways serve many different behaviors, the plasticity produced by this conditioning can change other behaviors. Thus, in animals or people with partial spinal cord injuries, appropriate reflex conditioning can improve locomotion. Furthermore, in people with spinal cord injuries, appropriate reflex conditioning can trigger widespread beneficial plasticity. This wider plasticity appears to reflect an iterative process through which the multiple behaviors in the individual{\textquoteright}s repertoire negotiate the properties of the spinal neurons and synapses that they all use. Operant-conditioning protocols are a promising new therapeutic method that could complement other rehabilitation methods and enhance functional recovery. Their successful use requires strict adherence to appropriately designed procedures, as well as close attention to accommodating and engaging the individual subject in the conditioning process.

}, keywords = {activity-dependent plasticity, H-Reflex, operant conditioning, Rehabilitation, spinal cord injury, spinal reflex}, issn = {1875-7855}, doi = {10.1016/bs.pbr.2015.02.002}, url = {http://www.ncbi.nlm.nih.gov/pubmed/25890136}, author = {Thompson, Aiko K and Jonathan Wolpaw} } @article {4215, title = {American Psychological Association Ann Mtg, Washington, DC}, year = {2014}, month = {08/2014}, author = {Jonathan Wolpaw} } @article {3370, title = {Brain-computer interface (BCI) evaluation in people with amyotrophic lateral sclerosis.}, journal = {Amyotroph Lateral Scler Frontotemporal Degener}, volume = {15}, year = {2014}, month = {06/2014}, pages = {207-15}, abstract = {Brain-computer interfaces (BCIs) might restore communication to people severely disabled by amyotrophic lateral sclerosis (ALS) or other disorders. We sought to: 1) define a protocol for determining whether a person with ALS can use a visual P300-based BCI; 2) determine what proportion of this population can use the BCI; and 3) identify factors affecting BCI performance. Twenty-five individuals with ALS completed an evaluation protocol using a standard 6 {\texttimes} 6 matrix and parameters selected by stepwise linear discrimination. With an 8-channel EEG montage, the subjects fell into two groups in BCI accuracy (chance accuracy 3\%). Seventeen averaged 92 ({\textpm} 3)\% (range 71-100\%), which is adequate for communication (G70 group). Eight averaged 12 ({\textpm} 6)\% (range 0-36\%), inadequate for communication (L40 subject group). Performance did not correlate with disability: 11/17 (65\%) of G70 subjects were severely disabled (i.e. ALSFRS-R < 5). All L40 subjects had visual impairments (e.g. nystagmus, diplopia, ptosis). P300 was larger and more anterior in G70 subjects. A 16-channel montage did not significantly improve accuracy. In conclusion, most people severely disabled by ALS could use a visual P300-based BCI for communication. In those who could not, visual impairment was the principal obstacle. For these individuals, auditory P300-based BCIs might be effective.}, keywords = {Adult, Aged, Amyotrophic Lateral Sclerosis, Biofeedback, Psychology, brain-computer interfaces, Communication Disorders, Electroencephalography, Event-Related Potentials, P300, Female, Humans, Male, Middle Aged, Online Systems, Photic Stimulation, Psychomotor Performance, Reaction Time}, issn = {2167-9223}, doi = {10.3109/21678421.2013.865750}, url = {http://www.ncbi.nlm.nih.gov/pubmed/24555843}, author = {McCane, Lynn M and Sellers, Eric W and Dennis J. McFarland and Mak, Joseph N and Carmack, C Steve and Zeitlin, Debra and Jonathan Wolpaw and Theresa M Vaughan} } @article {4217, title = {C. Warren Olanow Lecture}, year = {2014}, month = {06/2014}, abstract = {Mt. Sinai School of Medicine, New York, NY}, author = {Jonathan Wolpaw} } @article {4222, title = {Distinguished Lectures in Biological Engineering}, year = {2014}, month = {03/2014}, abstract = {EPFL, Lausanne, Switzerland}, author = {Jonathan Wolpaw} } @article {4220, title = {Invited Speaker}, year = {2014}, month = {04/2014}, abstract = {International Collaboration on Repair Discoveries (ICORD), Vancouver, BC}, author = {Jonathan Wolpaw} } @article {4223, title = {Invited Speaker}, year = {2014}, month = {03/2014}, abstract = {Brain Research Institute, ETH, Zurich, Switzerland}, author = {Jonathan Wolpaw} } @article {4218, title = {Keynote Speaker}, year = {2014}, month = {04/2014}, abstract = {UNYTE Translational Research Network, Univ of Rochester, NY}, author = {Jonathan Wolpaw} } @article {3390, title = {Locomotor impact of beneficial or nonbeneficial H-reflex conditioning after spinal cord injury.}, journal = {J Neurophysiol}, volume = {111}, year = {2014}, month = {03/2014}, pages = {1249-58}, abstract = {When new motor learning changes neurons and synapses in the spinal cord, it may affect previously learned behaviors that depend on the same spinal neurons and synapses. To explore these effects, we used operant conditioning to strengthen or weaken the right soleus H-reflex pathway in rats in which a right spinal cord contusion had impaired locomotion. When up-conditioning increased the H-reflex, locomotion improved. Steps became longer, and step-cycle asymmetry (i.e., limping) disappeared. In contrast, when down-conditioning decreased the H-reflex, locomotion did not worsen. Steps did not become shorter, and asymmetry did not increase. Electromyographic and kinematic analyses explained how H-reflex increase improved locomotion and why H-reflex decrease did not further impair it. Although the impact of up-conditioning or down-conditioning on the H-reflex pathway was still present during locomotion, only up-conditioning affected the soleus locomotor burst. Additionally, compensatory plasticity apparently prevented the weaker H-reflex pathway caused by down-conditioning from weakening the locomotor burst and further impairing locomotion. The results support the hypothesis that the state of the spinal cord is a "negotiated equilibrium" that serves all the behaviors that depend on it. When new learning changes the spinal cord, old behaviors undergo concurrent relearning that preserves or improves their key features. Thus, if an old behavior has been impaired by trauma or disease, spinal reflex conditioning, by changing a specific pathway and triggering a new negotiation, may enable recovery beyond that achieved simply by practicing the old behavior. Spinal reflex conditioning protocols might complement other neurorehabilitation methods and enhance recovery.}, keywords = {Animals, Conditioning, Operant, Female, H-Reflex, Learning, Locomotion, Male, Rats, Rats, Sprague-Dawley, Spinal Cord Injuries}, issn = {1522-1598}, doi = {10.1152/jn.00756.2013}, url = {http://www.ncbi.nlm.nih.gov/pubmed/24371288}, author = {Yi Chen and Lu Chen and Liu, Rongliang and Wang, Yu and Xiang Yang Chen and Jonathan Wolpaw} } @article {3384, title = {Long-term recording of external urethral sphincter EMG activity in unanesthetized, unrestrained rats.}, journal = {Am J Physiol Renal Physiol}, volume = {307}, year = {2014}, month = {08/2014}, pages = {F485-97}, abstract = {

The external urethral sphincter muscle (EUS) plays an important role in urinary function and often contributes to urinary dysfunction. EUS study would benefit from methodology for longitudinal recording of electromyographic activity (EMG) in unanesthetized animals, but this muscle is a poor substrate for chronic intramuscular electrodes, and thus the required methodology has not been available. We describe a method for long-term recording of EUS EMG by implantation of fine wires adjacent to the EUS that are secured to the pubic bone. Wires pass subcutaneously to a skull-mounted plug and connect to the recording apparatus by a flexible cable attached to a commutator. A force transducer-mounted cup under a metabolic cage collected urine, allowing recording of EUS EMG and voided urine weight without anesthesia or restraint. Implant durability permitted EUS EMG recording during repeated (up to 3 times weekly) 24-h sessions for more than 8 wk. EMG and voiding properties were stable over weeks 2-8. The degree of EUS phasic activity (bursting) during voiding was highly variable, with an average of 25\% of voids not exhibiting bursting. Electrode implantation adjacent to the EUS yielded stable EMG recordings over extended periods and eliminated the confounding effects of anesthesia, physical restraint, and the potential for dislodgment of the chronically implanted intramuscular electrodes. These results show that micturition in unanesthetized, unrestrained rats is usually, but not always, associated with EUS bursting. This methodology is applicable to studying EUS behavior during progression of gradually evolving disease and injury models and in response to therapeutic interventions.

}, keywords = {Animals, Electrodes, Implanted, Electromyography, Female, Pubic Bone, Rats, Rats, Sprague-Dawley, Urethra, Urination, Urodynamics}, issn = {1522-1466}, doi = {10.1152/ajprenal.00059.2014}, url = {http://www.ncbi.nlm.nih.gov/pubmed/24990895}, author = {LaPallo, Brandon K and Jonathan Wolpaw and Xiang Yang Chen and Jonathan S. Carp} } @article {4221, title = {Neurology Grand Rounds}, year = {2014}, month = {04/2014}, abstract = {Penn State University, Hershey, PA}, author = {Jonathan Wolpaw} } @article {3387, title = {Operant conditioning of spinal reflexes: from basic science to clinical therapy.}, journal = {Front Integr Neurosci}, volume = {8}, year = {2014}, month = {03/2014}, pages = {25}, abstract = {New appreciation of the adaptive capabilities of the nervous system, recent recognition that most spinal cord injuries are incomplete, and progress in enabling regeneration are generating growing interest in novel rehabilitation therapies. Here we review the 35-year evolution of one promising new approach, operant conditioning of spinal reflexes. This work began in the late 1970{\textquoteright}s as basic science; its purpose was to develop and exploit a uniquely accessible model for studying the acquisition and maintenance of a simple behavior in the mammalian central nervous system (CNS). The model was developed first in monkeys and then in rats, mice, and humans. Studies with it showed that the ostensibly simple behavior (i.e., a larger or smaller reflex) rests on a complex hierarchy of brain and spinal cord plasticity; and current investigations are delineating this plasticity and its interactions with the plasticity that supports other behaviors. In the last decade, the possible therapeutic uses of reflex conditioning have come under study, first in rats and then in humans. The initial results are very exciting, and they are spurring further studies. At the same time, the original basic science purpose and the new clinical purpose are enabling and illuminating each other in unexpected ways. The long course and current state of this work illustrate the practical importance of basic research and the valuable synergy that can develop between basic science questions and clinical needs.}, keywords = {H-Reflex, learning and memory, Locomotion, spinal cord injury, spinal cord plasticity}, issn = {1662-5145}, doi = {10.3389/fnint.2014.00025}, url = {http://www.ncbi.nlm.nih.gov/pubmed/24672441}, author = {Thompson, Aiko K and Jonathan Wolpaw} } @article {3385, title = {Operant conditioning of the soleus H-reflex does not induce long-term changes in the gastrocnemius H-reflexes and does not disturb normal locomotion in humans.}, journal = {J Neurophysiol}, volume = {112}, year = {2014}, month = {09/2014}, pages = {1439-46}, abstract = {

In normal animals, operant conditioning of the spinal stretch reflex or the H-reflex has lesser effects on synergist muscle reflexes. In rats and people with incomplete spinal cord injury (SCI), soleus H-reflex operant conditioning can improve locomotion. We studied in normal humans the impact of soleus H-reflex down-conditioning on medial (MG) and lateral gastrocnemius (LG) H-reflexes and on locomotion. Subjects completed 6 baseline and 30 conditioning sessions. During conditioning trials, the subject was encouraged to decrease soleus H-reflex size with the aid of visual feedback. Every sixth session, MG and LG H-reflexes were measured. Locomotion was assessed before and after conditioning. In successfully conditioned subjects, the soleus H-reflex decreased 27.2\%. This was the sum of within-session (task dependent) adaptation (13.2\%) and across-session (long term) change (14\%). The MG H-reflex decreased 14.5\%, due mainly to task-dependent adaptation (13.4\%). The LG H-reflex showed no task-dependent adaptation or long-term change. No consistent changes were detected across subjects in locomotor H-reflexes, EMG activity, joint angles, or step symmetry. Thus, in normal humans, soleus H-reflex down-conditioning does not induce long-term changes in MG/LG H-reflexes and does not change locomotion. In these subjects, task-dependent adaptation of the soleus H-reflex is greater than it is in people with SCI, whereas long-term change is less. This difference from results in people with SCI is consistent with the fact that long-term change is beneficial in people with SCI, since it improves locomotion. In contrast, in normal subjects, long-term change is not beneficial and may necessitate compensatory plasticity to preserve satisfactory locomotion.

}, keywords = {Learning, plasticity, Rehabilitation, Spinal Cord, synergists}, issn = {1522-1598}, doi = {10.1152/jn.00225.2014}, url = {http://www.ncbi.nlm.nih.gov/pubmed/24944216}, author = {Makihara, Yukiko and Segal, Richard L and Jonathan Wolpaw and Thompson, Aiko K} } @article {3383, title = {Persistent beneficial impact of H-reflex conditioning in spinal cord-injured rats.}, journal = {J Neurophysiol}, volume = {112}, year = {2014}, month = {11/2014}, pages = {2374-81}, abstract = {

Operant conditioning of a spinal cord reflex can improve locomotion in rats and humans with incomplete spinal cord injury. This study examined the persistence of its beneficial effects. In rats in which a right lateral column contusion injury had produced asymmetric locomotion, up-conditioning of the right soleus H-reflex eliminated the asymmetry while down-conditioning had no effect. After the 50-day conditioning period ended, the H-reflex was monitored for 100 [{\textpm}9 (SD)] (range 79-108) more days and locomotion was then reevaluated. After conditioning ended in up-conditioned rats, the H-reflex continued to increase, and locomotion continued to improve. In down-conditioned rats, the H-reflex decrease gradually disappeared after conditioning ended, and locomotion at the end of data collection remained as impaired as it had been before and immediately after down-conditioning. The persistence (and further progression) of H-reflex increase but not H-reflex decrease in these spinal cord-injured rats is consistent with the fact that up-conditioning improved their locomotion while down-conditioning did not. That is, even after up-conditioning ended, the up-conditioned H-reflex pathway remained adaptive because it improved locomotion. The persistence and further enhancement of the locomotor improvement indicates that spinal reflex conditioning protocols might supplement current therapies and enhance neurorehabilitation. They may be especially useful when significant spinal cord regeneration becomes possible and precise methods for retraining the regenerated spinal cord are needed.

}, keywords = {H-reflex conditioning, Learning, Locomotion, Memory, Motor control, Rehabilitation, spinal cord injury, spinal cord plasticity}, issn = {1522-1598}, doi = {10.1152/jn.00422.2014}, url = {http://www.ncbi.nlm.nih.gov/pubmed/25143542}, author = {Yi Chen and Lu Chen and Wang, Yu and Jonathan Wolpaw and Xiang Yang Chen} } @article {3386, title = {A practical, intuitive brain-computer interface for communicating {\textquoteright}yes{\textquoteright} or {\textquoteright}no{\textquoteright} by listening.}, journal = {J Neural Eng}, volume = {11}, year = {2014}, month = {06/2014}, pages = {035003}, abstract = {OBJECTIVE: Previous work has shown that it is possible to build an EEG-based binary brain-computer interface system (BCI) driven purely by shifts of attention to auditory stimuli. However, previous studies used abrupt, abstract stimuli that are often perceived as harsh and unpleasant, and whose lack of inherent meaning may make the interface unintuitive and difficult for beginners. We aimed to establish whether we could transition to a system based on more natural, intuitive stimuli (spoken words {\textquoteright}yes{\textquoteright} and {\textquoteright}no{\textquoteright}) without loss of performance, and whether the system could be used by people in the locked-in state. APPROACH: We performed a counterbalanced, interleaved within-subject comparison between an auditory streaming BCI that used beep stimuli, and one that used word stimuli. Fourteen healthy volunteers performed two sessions each, on separate days. We also collected preliminary data from two subjects with advanced amyotrophic lateral sclerosis (ALS), who used the word-based system to answer a set of simple yes-no questions. MAIN RESULTS: The N1, N2 and P3 event-related potentials elicited by words varied more between subjects than those elicited by beeps. However, the difference between responses to attended and unattended stimuli was more consistent with words than beeps. Healthy subjects{\textquoteright} performance with word stimuli (mean 77\% {\textpm} 3.3 s.e.) was slightly but not significantly better than their performance with beep stimuli (mean 73\% {\textpm} 2.8 s.e.). The two subjects with ALS used the word-based BCI to answer questions with a level of accuracy similar to that of the healthy subjects. SIGNIFICANCE: Since performance using word stimuli was at least as good as performance using beeps, we recommend that auditory streaming BCI systems be built with word stimuli to make the system more pleasant and intuitive. Our preliminary data show that word-based streaming BCI is a promising tool for communication by people who are locked in.}, keywords = {Adult, Aged, Algorithms, Auditory Perception, brain-computer interfaces, Communication Aids for Disabled, Electroencephalography, Equipment Design, Equipment Failure Analysis, Female, Humans, Male, Man-Machine Systems, Middle Aged, Quadriplegia, Treatment Outcome, User-Computer Interface}, issn = {1741-2552}, doi = {10.1088/1741-2560/11/3/035003}, url = {http://www.ncbi.nlm.nih.gov/pubmed/24838278}, author = {Jeremy Jeremy Hill and Ricci, Erin and Haider, Sameah and McCane, Lynn M and Susan M Heckman and Jonathan Wolpaw and Theresa M Vaughan} } @article {4212, title = {Satellite Symposium, Spinal Cord Plasticity in Motor Control, Washington, DC}, year = {2014}, month = {11/2014}, author = {Jonathan Wolpaw} } @article {3389, title = {The simplest motor skill: mechanisms and applications of reflex operant conditioning.}, journal = {Exerc Sport Sci Rev}, volume = {42}, year = {2014}, month = {04/2014}, pages = {82-90}, abstract = {Operant conditioning protocols can change spinal reflexes gradually, which are the simplest behaviors. This article summarizes the evidence supporting two propositions: that these protocols provide excellent models for defining the substrates of learning and that they can induce and guide plasticity to help restore skills, such as locomotion, that have been impaired by spinal cord injury or other disorders.}, keywords = {Animals, Conditioning, Operant, H-Reflex, Humans, Motor Skills, Muscle, Skeletal, Neuronal Plasticity, Reflex, Spinal Cord, Spinal Cord Injuries}, issn = {1538-3008}, doi = {10.1249/JES.0000000000000010}, url = {http://www.ncbi.nlm.nih.gov/pubmed/24508738}, author = {Thompson, Aiko K and Jonathan Wolpaw} } @article {4214, title = {Summer School on Neurorehabilitation, Baiona, Spain}, year = {2014}, month = {09/2014}, author = {Jonathan Wolpaw} } @article {4213, title = { Symposium, American Society of Neurorehabilitation, Washington, DC}, year = {2014}, month = {11/2014}, author = {Jonathan Wolpaw} } @article {4216, title = {Symposium Speaker}, year = {2014}, month = {06/2014}, abstract = {International Conference on NeuroRehabilitation, Aalborg, Denmark}, author = {Jonathan Wolpaw} } @article {4219, title = {Symposium Speaker}, year = {2014}, month = {05/2014}, abstract = {Sensorimotor Rehabilitation, University of Montreal, Canada}, author = {Jonathan Wolpaw} } @article {3083, title = {Adaptive Laplacian filtering for sensorimotor rhythm-based brain-computer interfaces.}, journal = {Journal of neural engineering}, volume = {10}, year = {2013}, month = {02/2013}, pages = {016002}, abstract = {OBJECTIVE: Sensorimotor rhythms (SMRs) are 8-30 Hz oscillations in the electroencephalogram (EEG) recorded from the scalp over sensorimotor cortex that change with movement and/or movement imagery. Many brain-computer interface (BCI) studies have shown that people can learn to control SMR amplitudes and can use that control to move cursors and other objects in one, two or three dimensions. At the same time, if SMR-based BCIs are to be useful for people with neuromuscular disabilities, their accuracy and reliability must be improved substantially. These BCIs often use spatial filtering methods such as common average reference (CAR), Laplacian (LAP) filter or common spatial pattern (CSP) filter to enhance the signal-to-noise ratio of EEG. Here, we test the hypothesis that a new filter design, called an {\textquoteright}adaptive Laplacian (ALAP) filter{\textquoteright}, can provide better performance for SMR-based BCIs. APPROACH: An ALAP filter employs a Gaussian kernel to construct a smooth spatial gradient of channel weights and then simultaneously seeks the optimal kernel radius of this spatial filter and the regularization parameter of linear ridge regression. This optimization is based on minimizing the leave-one-out cross-validation error through a gradient descent method and is computationally feasible. MAIN RESULTS: Using a variety of kinds of BCI data from a total of 22 individuals, we compare the performances of ALAP filter to CAR, small LAP, large LAP and CSP filters. With a large number of channels and limited data, ALAP performs significantly better than CSP, CAR, small LAP and large LAP both in classification accuracy and in mean-squared error. Using fewer channels restricted to motor areas, ALAP is still superior to CAR, small LAP and large LAP, but equally matched to CSP. SIGNIFICANCE: Thus, ALAP may help to improve the accuracy and robustness of SMR-based BCIs.}, keywords = {assistive communication, brain computer interface (BCI), brain-machine interface (BMI), electroencephalogram (EEG), leave-one-out (LOO) cross-validation, spatial filter}, issn = {1741-2552}, doi = {10.1088/1741-2560/10/1/016002}, url = {http://www.ncbi.nlm.nih.gov/pubmed/23220879}, author = {Lu, Jun and Dennis J. McFarland and Jonathan Wolpaw} } @article {3081, title = {Brain-computer interfaces.}, journal = {Handbook of clinical neurology}, volume = {110}, year = {2013}, pages = {67{\textendash}74}, abstract = {Brain-computer interfaces (BCIs) are systems that give their users communication and control capabilities that do not depend on muscles. The user\&$\#$39;s intentions are determined from activity recorded by electrodes on the scalp, on the cortical surface, or within the brain. BCIs can enable people who are paralyzed by amyotrophic lateral sclerosis (ALS), brainstem stroke, or other disorders to convey their needs and wishes to others, to operate word-processing programs or other software, or possibly to control a wheelchair or a neuroprosthesis. BCI technology might also augment rehabilitation protocols aimed at restoring useful motor function. With continued development and clinical implementation, BCIs could substantially improve the lives of those with severe disabilities.}, keywords = {Software}, issn = {0072-9752}, doi = {10.1016/B978-0-444-52901-5.00006-X}, url = {http://www.ncbi.nlm.nih.gov/pubmed/23312631}, author = {Jonathan Wolpaw} } @article {3080, title = {Operant conditioning of a spinal reflex can improve locomotion after spinal cord injury in humans.}, journal = {The Journal of neuroscience : the official journal of the Society for Neuroscience}, volume = {33}, year = {2013}, month = {02/2013}, pages = {2365{\textendash}2375}, abstract = {Operant conditioning protocols can modify the activity of specific spinal cord pathways and can thereby affect behaviors that use these pathways. To explore the therapeutic application of these protocols, we studied the impact of down-conditioning the soleus H-reflex in people with impaired locomotion caused by chronic incomplete spinal cord injury. After a baseline period in which soleus H-reflex size was measured and locomotion was assessed, subjects completed either 30 H-reflex down-conditioning sessions (DC subjects) or 30 sessions in which the H-reflex was simply measured [unconditioned (UC) subjects], and locomotion was reassessed. Over the 30 sessions, the soleus H-reflex decreased in two-thirds of the DC subjects (a success rate similar to that in normal subjects) and remained smaller several months later. In these subjects, locomotion became faster and more symmetrical, and the modulation of EMG activity across the step cycle increased bilaterally. Furthermore, beginning about halfway through the conditioning sessions, all of these subjects commented spontaneously that they were walking faster and farther in their daily lives, and several noted less clonus, easier stepping, and/or other improvements. The H-reflex did not decrease in the other DC subjects or in any of the UC subjects; and their locomotion did not improve. These results suggest that reflex-conditioning protocols can enhance recovery of function after incomplete spinal cord injuries and possibly in other disorders as well. Because they are able to target specific spinal pathways, these protocols could be designed to address each individual{\textquoteright}s particular deficits, and might thereby complement other rehabilitation methods.}, keywords = {Learning, Locomotion, operant conditioning, plasticity, Rehabilitation, spasticity}, issn = {1529-2401}, doi = {10.1523/JNEUROSCI.3968-12.2013}, url = {http://www.ncbi.nlm.nih.gov/pubmed/23392666}, author = {Thompson, Aiko K. and Pomerantz, Ferne R. and Jonathan Wolpaw} } @article {3082, title = {Soleus H-reflex operant conditioning changes the H-reflex recruitment curve.}, journal = {Muscle \& nerve}, volume = {47}, year = {2013}, month = {04/2013}, pages = {539{\textendash}544}, abstract = {INTRODUCTION: Operant conditioning can gradually change the human soleus H-reflex. The protocol conditions the reflex near M-wave threshold. In this study we examine its impact on the reflexes at other stimulus strengths. METHODS: H-reflex recruitment curves were obtained before and after a 24-session exposure to an up-conditioning (HRup) or a down-conditioning (HRdown) protocol and were compared. RESULTS: In both HRup and HRdown subjects, conditioning affected the entire H-reflex recruitment curve. In 5 of 6 HRup and 3 of 6 HRdown subjects, conditioning elevated (HRup) or depressed (HRdown), respectively, the entire curve. In the other HRup subject or the other 3 HRdown subjects, the curve was shifted to the left or to the right, respectively. CONCLUSIONS: H-reflex conditioning does not simply change the H-reflex to a stimulus of particular strength; it also changes the H-reflexes to stimuli of different strengths. Thus, it is likely to affect many actions in which this pathway participates.}, keywords = {motor learning, plasticity, Rehabilitation, Spinal Cord}, issn = {1097-4598}, doi = {10.1002/mus.23620}, url = {http://www.ncbi.nlm.nih.gov/pubmed/23281107}, author = {Thompson, Aiko K. and Xiang Yang Chen and Jonathan Wolpaw} } @inbook {2865, title = {BCIs That Use Electrocorticographic Activity.}, booktitle = {Brain-Computer Interfaces: Principles and Practice}, year = {2012}, publisher = {Oxford University Press}, organization = {Oxford University Press}, abstract = {This chapter discusses the potential of electrocorticography (ECoG) as a clinically useful brain-computer interface signal modality. ECoG has greater amplitude, higher topographical resolution, and a much broader frequency range than scalp-recorded electroencephalography and is less susceptible to artifacts. With current and foreseeable recording methodologies, ECoG is likely to have greater long-term stability than intracortically recorded signals. Furthermore, it can more readily be recorded from larger cortical areas, and it requires much lower digitization rates, thus greatly reducing the power requirements of wholly implanted systems.}, keywords = {brain signals, brain-computer interfaces, ECoG, intracortically recorded signals}, issn = {ISBN: 978-0195388855}, doi = {10.1093/acprof:oso/9780195388855.003.0015}, url = {http://www.oxfordscholarship.com/view/10.1093/acprof:oso/9780195388855.001.0001/acprof-9780195388855-chapter-015}, author = {Jonathan Wolpaw and E. Winter-Wolpaw and Gerwin Schalk} } @article {3087, title = {Brain-computer interfaces in medicine.}, journal = {Mayo Clinic proceedings. Mayo Clinic}, volume = {87}, year = {2012}, month = {03/2012}, pages = {268{\textendash}279}, abstract = {Brain-computer interfaces (BCIs) acquire brain signals, analyze them, and translate them into commands that are relayed to output devices that carry out desired actions. BCIs do not use normal neuromuscular output pathways. The main goal of BCI is to replace or restore useful function to people disabled by neuromuscular disorders such as amyotrophic lateral sclerosis, cerebral palsy, stroke, or spinal cord injury. From initial demonstrations of electroencephalography-based spelling and single-neuron-based device control, researchers have gone on to use electroencephalographic, intracortical, electrocorticographic, and other brain signals for increasingly complex control of cursors, robotic arms, prostheses, wheelchairs, and other devices. Brain-computer interfaces may also prove useful for rehabilitation after stroke and for other disorders. In the future, they might augment the performance of surgeons or other medical professionals. Brain-computer interface technology is the focus of a rapidly growing research and development enterprise that is greatly exciting scientists, engineers, clinicians, and the public in general. Its future achievements will depend on advances in 3 crucial areas. Brain-computer interfaces need signal-acquisition hardware that is convenient, portable, safe, and able to function in all environments. Brain-computer interface systems need to be validated in long-term studies of real-world use by people with severe disabilities, and effective and viable models for their widespread dissemination must be implemented. Finally, the day-to-day and moment-to-moment reliability of BCI performance must be improved so that it approaches the reliability of natural muscle-based function.}, keywords = {User-Computer Interface}, issn = {1942-5546}, doi = {10.1016/j.mayocp.2011.12.008}, url = {http://www.ncbi.nlm.nih.gov/pubmed/22325364}, author = {Shih, Jerry J. and Krusienski, Dean J. and Jonathan Wolpaw} } @article {3084, title = {Cortical stimulation causes long-term changes in H-reflexes and spinal motoneuron GABA receptors.}, journal = {Journal of neurophysiology}, volume = {108}, year = {2012}, month = {11/2012}, pages = {2668{\textendash}2678}, abstract = {The cortex gradually modifies the spinal cord during development, throughout later life, and in response to trauma or disease. The mechanisms of this essential function are not well understood. In this study, weak electrical stimulation of rat sensorimotor cortex increased the soleus H-reflex, increased the numbers and sizes of GABAergic spinal interneurons and GABAergic terminals on soleus motoneurons, and decreased GABA(A) and GABA(B) receptor labeling in these motoneurons. Several months after the stimulation ended the interneuron and terminal increases had disappeared, but the H-reflex increase and the receptor decreases remained. The changes in GABAergic terminals and GABA(B) receptors accurately predicted the changes in H-reflex size. The results reveal a new long-term dimension to cortical-spinal interactions and raise new therapeutic possibilities.}, keywords = {Spinal Cord}, issn = {1522-1598}, doi = {10.1152/jn.00516.2012}, url = {http://www.ncbi.nlm.nih.gov/pubmed/22933718}, author = {Wang, Yu and Yi Chen and Lu Chen and Jonathan Wolpaw and Xiang Yang Chen} } @article {3086, title = {EEG correlates of P300-based brain-computer interface (BCI) performance in people with amyotrophic lateral sclerosis.}, journal = {Journal of neural engineering}, volume = {9}, year = {2012}, month = {04/2012}, pages = {026014}, abstract = {The purpose of this study was to identify electroencephalography (EEG) features that correlate with P300-based brain-computer interface (P300 BCI) performance in people with amyotrophic lateral sclerosis (ALS). Twenty people with ALS used a P300 BCI spelling application in copy-spelling mode. Three types of EEG features were found to be good predictors of P300 BCI performance: (1) the root-mean-square amplitude and (2) the negative peak amplitude of the event-related potential to target stimuli (target ERP) at Fz, Cz, P3, Pz, and P4; and (3) EEG theta frequency (4.5-8 Hz) power at Fz, Cz, P3, Pz, P4, PO7, PO8 and Oz. A statistical prediction model that used a subset of these features accounted for \>60\% of the variance in copy-spelling performance (p \< 0.001, mean R(2)?= 0.6175). The correlations reflected between-subject, rather than within-subject, effects. The results enhance understanding of performance differences among P300 BCI users. The predictors found in this study might help in: (1) identifying suitable candidates for long-term P300 BCI operation; (2) assessing performance online. Further work on within-subject effects needs to be done to establish whether P300 BCI user performance could be improved by optimizing one or more of these EEG features.}, keywords = {User-Computer Interface}, issn = {1741-2552}, doi = {10.1088/1741-2560/9/2/026014}, url = {http://www.ncbi.nlm.nih.gov/pubmed/22350501}, author = {Mak, Joseph N. and Dennis J. McFarland and Theresa M Vaughan and McCane, Lynn M. and Tsui, Phillippa Z. and Zeitlin, Debra J. and Sellers, Eric W. and Jonathan Wolpaw} } @inbook {2539, title = {Hardware and Software Technologies.}, booktitle = {Brain-Computer Interfaces: Principles and Practice}, year = {2012}, publisher = {Oxford University Press}, organization = {Oxford University Press}, issn = {978-0195388855}, author = {Gerwin Schalk and Guger, C and Adam J Wilson}, editor = {Jonathan Wolpaw and E. Winter-Wolpaw} } @article {3085, title = {Harnessing neuroplasticity for clinical applications.}, journal = {Brain : a journal of neurology}, volume = {135}, year = {2012}, month = {04/2012}, pages = {e215; author reply e216}, keywords = {Neuronal Plasticity}, issn = {1460-2156}, doi = {10.1093/brain/aws017}, url = {http://www.ncbi.nlm.nih.gov/pubmed/22374936}, author = {Jonathan Wolpaw} } @article {3088, title = {H-reflex modulation in the human medial and lateral gastrocnemii during standing and walking.}, journal = {Muscle \& nerve}, volume = {45}, year = {2012}, month = {01/2012}, pages = {116{\textendash}125}, abstract = {INTRODUCTION: The soleus H-reflex is dynamically modulated during walking. However, modulation of the gastrocnemii H-reflexes has not been studied systematically. METHODS: The medial and lateral gastrocnemii (MG and LG) and soleus H-reflexes were measured during standing and walking in humans. RESULTS: Maximum H-reflex amplitude was significantly smaller in MG (mean 1.1 mV) or LG (1.1 mV) than in soleus (3.3 mV). Despite these size differences, the reflex amplitudes of the three muscles were positively correlated. The MG and LG H-reflexes were phase- and task-dependently modulated in ways similar to the soleus H-reflex. CONCLUSIONS: Although there are anatomical and physiological differences between the soleus and gastrocnemii muscles, the reflexes of the three muscles are similarly modulated during walking and between standing and walking. Our findings support the hypothesis that these reflexes are synergistically modulated during walking to facilitate ongoing movement.}, keywords = {Locomotion, phase-dependent modulation, spinal reflex, synergist, task-dependent modulation}, issn = {1097-4598}, doi = {10.1002/mus.22265}, url = {http://www.ncbi.nlm.nih.gov/pubmed/22190317}, author = {Makihara, Yukiko and Segal, Richard L. and Jonathan Wolpaw and Thompson, Aiko K.} } @article {3399, title = {Value of amplitude, phase, and coherence features for a sensorimotor rhythm-based brain-computer interface.}, journal = {Brain Res Bull}, volume = {87}, year = {2012}, month = {01/2012}, pages = {130-4}, abstract = {Measures that quantify the relationship between two or more brain signals are drawing attention as neuroscientists explore the mechanisms of large-scale integration that enable coherent behavior and cognition. Traditional Fourier-based measures of coherence have been used to quantify frequency-dependent relationships between two signals. More recently, several off-line studies examined phase-locking value (PLV) as a possible feature for use in brain-computer interface (BCI) systems. However, only a few individuals have been studied and full statistical comparisons among the different classes of features and their combinations have not been conducted. The present study examines the relative BCI performance of spectral power, coherence, and PLV, alone and in combination. The results indicate that spectral power produced classification at least as good as PLV, coherence, or any possible combination of these measures. This may be due to the fact that all three measures reflect mainly the activity of a single signal source (i.e., an area of sensorimotor cortex). This possibility is supported by the finding that EEG signals from different channels generally had near-zero phase differences. Coherence, PLV, and other measures of inter-channel relationships may be more valuable for BCIs that use signals from more than one distinct cortical source.}, keywords = {Algorithms, Brain, Electroencephalography, Humans, Motor Cortex, User-Computer Interface}, issn = {1873-2747}, doi = {10.1016/j.brainresbull.2011.09.019}, url = {http://www.ncbi.nlm.nih.gov/pubmed/21985984}, author = {Krusienski, Dean J and Dennis J. McFarland and Jonathan Wolpaw} } @article {3123, title = {Brain-Computer Interfaces for Communication and Control.}, journal = {Communications of the ACM}, volume = {54}, year = {2011}, month = {05/2011}, pages = {60{\textendash}66}, issn = {0001-0782}, doi = {10.1145/1941487.1941506}, url = {http://www.ncbi.nlm.nih.gov/pubmed/21984822}, author = {Dennis J. McFarland and Jonathan Wolpaw} } @article {3090, title = {Operant conditioning of rat soleus H-reflex oppositely affects another H-reflex and changes locomotor kinematics.}, journal = {The Journal of neuroscience : the official journal of the Society for Neuroscience}, volume = {31}, year = {2011}, month = {08/2011}, pages = {11370{\textendash}11375}, abstract = {H-reflex conditioning is a model for studying the plasticity associated with a new motor skill. We are exploring its effects on other reflexes and on locomotion. Rats were implanted with EMG electrodes in both solei (SOL(R) and SOL(L)) and right quadriceps (QD(R)), and stimulating cuffs on both posterior tibial (PT) nerves and right posterior femoral nerve. When SOL(R) EMG remained in a defined range, PT(R) stimulation just above M-response threshold elicited the SOL(R) H-reflex. Analogous procedures elicited the QD(R) and SOL(L) H-reflexes. After a control period, each rat was exposed for 50 d to a protocol that rewarded SOL(R) H-reflexes that were above (HRup rats) or below (HRdown rats) a criterion. HRup conditioning increased the SOL(R) H-reflex to 214 {\textpm} 37\% (mean {\textpm} SEM) of control (p = 0.02) and decreased the QD(R) H-reflex to 71 {\textpm} 26\% (p = 0.06). HRdown conditioning decreased the SOL(R) H-reflex to 69 {\textpm} 2\% (p < 0.001) and increased the QD(R) H-reflex to 121 {\textpm} 7\% (p = 0.02). These changes remained during locomotion. The SOL(L) H-reflex did not change. During the stance phase of locomotion, ankle plantarflexion increased in HRup rats and decreased in HRdown rats, hip extension did the opposite, and hip height did not change. The plasticity that changes the QD(R) H-reflex and locomotor kinematics may be inevitable (i.e., reactive) due to the ubiquity of activity-dependent CNS plasticity, and/or necessary (i.e., compensatory) to preserve other behaviors (e.g., locomotion) that would otherwise be disturbed by the change in the SOL(R) H-reflex pathway. The changes in joint angles, coupled with the preservation of hip height, suggest that compensatory plasticity did occur.}, keywords = {Rats, Sprague-Dawley}, issn = {1529-2401}, doi = {10.1523/JNEUROSCI.1526-11.2011}, url = {http://www.ncbi.nlm.nih.gov/pubmed/21813696}, author = {Yi Chen and Lu Chen and Wang, Yu and Jonathan Wolpaw and Xiang Yang Chen} } @article {3096, title = {The P300-based brain-computer interface (BCI): effects of stimulus rate.}, journal = {Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology}, volume = {122}, year = {2011}, month = {04/2011}, pages = {731{\textendash}737}, abstract = {OBJECTIVE: Brain-computer interface technology can restore communication and control to people who are severely paralyzed. We have developed a non-invasive BCI based on the P300 event-related potential that uses an 8{\texttimes}9 matrix of 72 items that flash in groups of 6. Stimulus presentation rate (i.e., flash rate) is one of several parameters that could affect the speed and accuracy of performance. We studied performance (i.e., accuracy and characters/min) on copy spelling as a function of flash rate. METHODS: In the first study of six BCI users, stimulus-on and stimulus-off times were equal and flash rate was 4, 8, 16, or 32 Hz. In the second study of five BCI users, flash rate was varied by changing either the stimulus-on or stimulus-off time. RESULTS: For all users, lower flash rates gave higher accuracy. The flash rate that gave the highest characters/min varied across users, ranging from 8 to 32 Hz. However, variations in stimulus-on and stimulus-off times did not themselves significantly affect accuracy. Providing feedback did not affect results in either study suggesting that offline analyses should readily generalize to online performance. However there do appear to be session-specific effects that can influence the generalizability of classifier results. CONCLUSIONS: The results show that stimulus presentation (i.e., flash) rate affects the accuracy and speed of P300 BCI performance. SIGNIFICANCE: These results extend the range over which slower flash rates increase the amplitude of the P300. Considering also presentation time, the optimal rate differs among users, and thus should be set empirically for each user. Optimal flash rate might also vary with other parameters such as the number of items in the matrix.}, keywords = {brain-computer interface, neuroprosthesis, P300}, issn = {1872-8952}, doi = {10.1016/j.clinph.2010.10.029}, url = {http://www.ncbi.nlm.nih.gov/pubmed/21067970}, author = {Dennis J. McFarland and Sarnacki, William A. and Townsend, George and Theresa M Vaughan and Jonathan Wolpaw} } @article {3091, title = {Should the parameters of a BCI translation algorithm be continually adapted?.}, journal = {Journal of neuroscience methods}, volume = {199}, year = {2011}, month = {07/2011}, pages = {103{\textendash}107}, abstract = {People with or without motor disabilities can learn to control sensorimotor rhythms (SMRs) recorded from the scalp to move a computer cursor in one or more dimensions or can use the P300 event-related potential as a control signal to make discrete selections. Data collected from individuals using an SMR-based or P300-based BCI were evaluated offline to estimate the impact on performance of continually adapting the parameters of the translation algorithm during BCI operation. The performance of the SMR-based BCI was enhanced by adaptive updating of the feature weights or adaptive normalization of the features. In contrast, P300 performance did not benefit from either of these procedures.}, keywords = {adaptation, brain-computer interface, EEG}, issn = {1872-678X}, doi = {10.1016/j.jneumeth.2011.04.037}, url = {http://www.ncbi.nlm.nih.gov/pubmed/21571004}, author = {Dennis J. McFarland and Sarnacki, William A. and Jonathan Wolpaw} } @article {2150, title = {Spatiotemporal dynamics of electrocorticographic high gamma activity during overt and covert word repetition.}, journal = {Neuroimage}, volume = {54}, year = {2011}, month = {02/2011}, pages = {2960-72}, abstract = {

Language is one of the defining abilities of humans. Many studies have characterized the neural correlates of different aspects of language processing. However, the imaging techniques typically used in these studies were limited in either their temporal or spatial resolution. Electrocorticographic (ECoG) recordings from the surface of the\ brain\ combine high spatial with high temporal resolution and thus could be a valuable tool for the study of neural correlates of language function. In this study, we defined the spatiotemporal dynamics of ECoG activity during a word repetition task in nine human subjects. ECoG was recorded while each subject overtly or covertly repeated words that were presented either visually or auditorily. ECoG amplitudes in the high gamma (HG) band confidently tracked neural changes associated with stimulus presentation and with the subject{\textquoteright}s verbal response. Overt word production was primarily associated with HG changes in the superior and middle parts of temporal lobe, Wernicke{\textquoteright}s area, the supramarginal gyrus, Broca{\textquoteright}s area, premotor cortex (PMC), primary motor cortex. Covert word production was primarily associated with HG changes in superior temporal lobe and the supramarginal gyrus. Acoustic processing from both auditory stimuli as well as the subject{\textquoteright}s own voice resulted in HG power changes in superior temporal lobe and Wernicke{\textquoteright}s area. In summary, this study represents a comprehensive characterization of overt and covert speech using electrophysiological imaging with high spatial and temporal resolution. It thereby complements the findings of previous neuroimaging studies of language and thus further adds to\ current\ understanding of word processing in humans.

}, keywords = {Adolescent, Adult, Brain, Brain Mapping, Electroencephalography, Female, Humans, Male, Middle Aged, Signal Processing, Computer-Assisted, Verbal Behavior}, issn = {1095-9572}, doi = {10.1016/j.neuroimage.2010.10.029}, url = {http://www.ncbi.nlm.nih.gov/pubmed/21029784}, author = {Pei, Xiao-Mei and Leuthardt, E C and Charles M Gaona and Peter Brunner and Jonathan Wolpaw and Gerwin Schalk} } @article {3092, title = {Special issue containing contributions from the Fourth International Brain-Computer Interface Meeting.}, journal = {Journal of neural engineering}, volume = {8}, year = {2011}, month = {04/2011}, pages = {020201}, keywords = {User-Computer Interface}, issn = {1741-2552}, doi = {10.1088/1741-2560/8/2/020201}, url = {http://www.ncbi.nlm.nih.gov/pubmed/21436522}, author = {Theresa M Vaughan and Jonathan Wolpaw} } @article {3093, title = {Trained modulation of sensorimotor rhythms can affect reaction time.}, journal = {Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology}, volume = {122}, year = {2011}, month = {09/2011}, pages = {1820{\textendash}1826}, abstract = {OBJECTIVE: Brain-computer interface (BCI) technology might be useful for rehabilitation of motor function. This speculation is based on the premise that modifying the EEG will modify behavior, a proposition for which there is limited empirical data. The present study examined the possibility that voluntary modulation of sensorimotor rhythm (SMR) can affect motor behavior in normal human subjects. METHODS: Six individuals performed a cued-reaction task with variable warning periods. A typical variable foreperiod effect was associated with SMR desynchronization. SMR features that correlated with reaction times were then used to control a two-target cursor movement BCI task. Following successful BCI training, an uncued reaction time task was embedded within the cursor movement task. RESULTS: Voluntarily increasing SMR beta rhythms was associated with longer reaction times than decreasing SMR beta rhythms. CONCLUSIONS: Voluntary modulation of EEG SMR can affect motor behavior. SIGNIFICANCE: These results encourage studies that integrate BCI training into rehabilitation protocols and examine its capacity to augment restoration of useful motor function.}, keywords = {brain-computer interface, EEG, Reaction Time}, issn = {1872-8952}, doi = {10.1016/j.clinph.2011.02.016}, url = {http://www.ncbi.nlm.nih.gov/pubmed/21411366}, author = {Chadwick B. Boulay and Sarnacki, W. A. and Jonathan Wolpaw and Dennis J. McFarland} } @article {3101, title = {A brain-computer interface for long-term independent home use.}, journal = {Amyotrophic lateral sclerosis : official publication of the World Federation of Neurology Research Group on Motor Neuron Diseases}, volume = {11}, year = {2010}, month = {10/2010}, pages = {449{\textendash}455}, abstract = {Our objective was to develop and validate a new brain-computer interface (BCI) system suitable for long-term independent home use by people with severe motor disabilities. The BCI was used by a 51-year-old male with ALS who could no longer use conventional assistive devices. Caregivers learned to place the electrode cap, add electrode gel, and turn on the BCI. After calibration, the system allowed the user to communicate via EEG. Re-calibration was performed remotely (via the internet), and BCI accuracy assessed in periodic tests. Reports of BCI usefulness by the user and the family were also recorded. Results showed that BCI accuracy remained at 83\% (r = -.07, n.s.) for over 2.5 years (1.4\% expected by chance). The BCI user and his family state that the BCI had restored his independence in social interactions and at work. He uses the BCI to run his NIH-funded research laboratory and to communicate via e-mail with family, friends, and colleagues. In addition to this first user, several other similarly disabled people are now using the BCI in their daily lives. In conclusion, long-term independent home use of this BCI system is practical for severely disabled people, and can contribute significantly to quality of life and productivity.}, keywords = {User-Computer Interface}, issn = {1471-180X}, doi = {10.3109/17482961003777470}, url = {http://www.ncbi.nlm.nih.gov/pubmed/20583947}, author = {Sellers, Eric W. and Theresa M Vaughan and Jonathan Wolpaw} } @article {3094, title = {Brain-computer interface research comes of age: traditional assumptions meet emerging realities.}, journal = {Journal of motor behavior}, volume = {42}, year = {2010}, month = {11/2010}, pages = {351{\textendash}353}, abstract = {Brain-computer interfaces (BCIs) could provide important new communication and control options for people with severe motor disabilities. Most BCI research to date has been based on 4 assumptions that: (a) intended actions are fully represented in the cerebral cortex; (b) neuronal action potentials can provide the best picture of an intended action; (c) the best BCI is one that records action potentials and decodes them; and (d) ongoing mutual adaptation by the BCI user and the BCI system is not very important. In reality, none of these assumptions is presently defensible. Intended actions are the products of many areas, from the cortex to the spinal cord, and the contributions of each area change continually as the CNS adapts to optimize performance. BCIs must track and guide these adaptations if they are to achieve and maintain good performance. Furthermore, it is not yet clear which category of brain signals will prove most effective for BCI applications. In human studies to date, low-resolution electroencephalography-based BCIs perform as well as high-resolution cortical neuron-based BCIs. In sum, BCIs allow their users to develop new skills in which the users control brain signals rather than muscles. Thus, the central task of BCI research is to determine which brain signals users can best control, to maximize that control, and to translate it accurately and reliably into actions that accomplish the users{\textquoteright} intentions.}, keywords = {brain-computer interface, brain-machine interface, EEG, human, neuroprosthesis}, issn = {1940-1027}, doi = {10.1080/00222895.2010.526471}, url = {http://www.ncbi.nlm.nih.gov/pubmed/21184352}, author = {Jonathan Wolpaw} } @article {3105, title = {A comparison of regression techniques for a two-dimensional sensorimotor rhythm-based brain-computer interface.}, journal = {Journal of neural engineering}, volume = {7}, year = {2010}, month = {02/2010}, pages = {16003}, abstract = {People can learn to control electroencephalogram (EEG) features consisting of sensorimotor-rhythm amplitudes and use this control to move a cursor in one, two or three dimensions to a target on a video screen. This study evaluated several possible alternative models for translating these EEG features into two-dimensional cursor movement by building an offline simulation using data collected during online performance. In offline comparisons, support-vector regression (SVM) with a radial basis kernel produced somewhat better performance than simple multiple regression, the LASSO or a linear SVM. These results indicate that proper choice of a translation algorithm is an important factor in optimizing brain-computer interface (BCI) performance, and provide new insight into algorithm choice for multidimensional movement control.}, keywords = {Young Adult}, issn = {1741-2552}, doi = {10.1088/1741-2560/7/1/016003}, url = {http://www.ncbi.nlm.nih.gov/pubmed/20075503}, author = {Fruitet, Joan and Dennis J. McFarland and Jonathan Wolpaw} } @article {2200, title = {Does the {\textquoteright}P300{\textquoteright} speller depend on eye gaze?.}, journal = {J Neural Eng}, volume = {7}, year = {2010}, month = {10/2010}, pages = {056013}, abstract = {

Many people affected by debilitating neuromuscular disorders such as amyotrophic lateral sclerosis, brainstem stroke or spinal cord injury are impaired in their ability to, or are even unable to, communicate. A brain-computer interface (BCI) uses brain signals, rather than muscles, to re-establish communication with the outside world. One particular BCI approach is the so-called {\textquoteright}P300 matrix speller{\textquoteright} that was first described by Farwell and Donchin (1988 Electroencephalogr. Clin. Neurophysiol. 70 510-23). It has been widely assumed that this method does not depend on the ability to focus on the desired character, because it was thought that it relies primarily on the P300-evoked potential and minimally, if at all, on other EEG features such as the visual-evoked potential (VEP). This issue is highly relevant for the clinical application of this BCI method, because eye movements may be impaired or lost in the relevant user population. This study investigated the extent to which the performance in a {\textquoteright}P300{\textquoteright} speller BCI depends on eye gaze. We evaluated the performance of 17 healthy subjects using a {\textquoteright}P300{\textquoteright} matrix speller under two conditions. Under one condition ({\textquoteright}letter{\textquoteright}), the subjects focused their eye gaze on the intended letter, while under the second condition ({\textquoteright}center{\textquoteright}), the subjects focused their eye gaze on a fixation cross that was located in the center of the matrix. The results show that the performance of the {\textquoteright}P300{\textquoteright} matrix speller in normal subjects depends in considerable measure on gaze direction. They thereby disprove a widespread assumption in BCI research, and suggest that this BCI might function more effectively for people who retain some eye-movement control. The applicability of these findings to people with severe neuromuscular disabilities (particularly in eye-movements) remains to be determined.

}, keywords = {Adult, Event-Related Potentials, P300, Eye Movements, Female, Humans, Male, Middle Aged, Models, Neurological, Photic Stimulation, User-Computer Interface, Young Adult}, issn = {1741-2552}, doi = {10.1088/1741-2560/7/5/056013}, url = {http://www.ncbi.nlm.nih.gov/pubmed/20858924}, author = {Peter Brunner and Joshi, S and S Briskin and Jonathan Wolpaw and H Bischof and Gerwin Schalk} } @article {3103, title = {Electroencephalographic (EEG) control of three-dimensional movement.}, journal = {Journal of neural engineering}, volume = {7}, year = {2010}, month = {06/2010}, pages = {036007}, abstract = {Brain-computer interfaces (BCIs) can use brain signals from the scalp (EEG), the cortical surface (ECoG), or within the cortex to restore movement control to people who are paralyzed. Like muscle-based skills, BCIs{\textquoteright} use requires activity-dependent adaptations in the brain that maintain stable relationships between the person{\textquoteright}s intent and the signals that convey it. This study shows that humans can learn over a series of training sessions to use EEG for three-dimensional control. The responsible EEG features are focused topographically on the scalp and spectrally in specific frequency bands. People acquire simultaneous control of three independent signals (one for each dimension) and reach targets in a virtual three-dimensional space. Such BCI control in humans has not been reported previously. The results suggest that with further development noninvasive EEG-based BCIs might control the complex movements of robotic arms or neuroprostheses.}, keywords = {User-Computer Interface}, issn = {1741-2552}, doi = {10.1088/1741-2560/7/3/036007}, url = {http://www.ncbi.nlm.nih.gov/pubmed/20460690}, author = {Dennis J. McFarland and Sarnacki, William A. and Jonathan Wolpaw} } @article {3102, title = {External urethral sphincter motoneuron properties in adult female rats studied in vitro.}, journal = {Journal of neurophysiology}, volume = {104}, year = {2010}, month = {09/2010}, pages = {1286{\textendash}1300}, abstract = {The external urethral sphincter (EUS) muscle plays a crucial role in lower urinary tract function: its activation helps maintain continence, whereas its relaxation contributes to micturition. To determine how the intrinsic properties of its motoneurons contribute to its physiological function, we have obtained intracellular current-clamp recordings from 49 EUS motoneurons in acutely isolated spinal cord slices from adult female rats. In all, 45\% of EUS motoneurons fired spontaneously and steadily (average rate = 12-27 pulses/s). EUS motoneurons were highly excitable, having lower rheobase, higher input resistance, and smaller threshold depolarization than those of rat hindlimb motoneurons recorded in vitro. Correlations between these properties and afterhyperpolarization half-decay time are consistent with EUS motoneurons having characteristics of both fast and slow motor unit types. EUS motoneurons with a slow-like spectrum of properties exhibited spontaneous firing more often than those with fast-like characteristics. During triangular current ramp-induced repetitive firing, recruitment typically occurred at lower current levels than those at derecruitment, although the opposite pattern occurred in 10\% of EUS motoneurons. This percentage was likely underestimated due to firing rate adaptation. These findings are consistent with the presence of a basal level of persistent inward current (PIC) in at least some EUS motoneurons. The low EUS motoneuron current and voltage thresholds make them readily recruitable, rendering them well suited to their physiological role in continence. The expression of firing behaviors consistent with PIC activation in this highly reduced preparation raises the possibility that in the intact animal, PICs contribute to urinary function not only through neuromodulator-dependent but also through neuromodulator-independent mechanisms.}, keywords = {Urethra}, issn = {1522-1598}, doi = {10.1152/jn.00224.2010}, url = {http://www.ncbi.nlm.nih.gov/pubmed/20573976}, author = {Jonathan S. Carp and Tennissen, Ann M. and Liebschutz, Jennifer E. and Xiang Yang Chen and Jonathan Wolpaw} } @article {3095, title = {H-reflex up-conditioning encourages recovery of EMG activity and H-reflexes after sciatic nerve transection and repair in rats.}, journal = {The Journal of neuroscience : the official journal of the Society for Neuroscience}, volume = {30}, year = {2010}, month = {12/2010}, pages = {16128{\textendash}16136}, abstract = {Operant conditioning of the spinal stretch reflex or its electrical analog, the H-reflex, produces spinal cord plasticity and can thereby affect motoneuron responses to primary afferent input. To explore whether this conditioning can affect the functional outcome after peripheral nerve injury, we assessed the effect of up-conditioning soleus (SOL) H-reflex on SOL and tibialis anterior (TA) function after sciatic nerve transection and repair. Sprague Dawley rats were implanted with EMG electrodes in SOL and TA and stimulating cuffs on the posterior tibial nerve. After control data collection, the sciatic nerve was transected and repaired and the rat was exposed for 120 d to continued control data collection (TC rats) or SOL H-reflex up-conditioning (TU rats). At the end of data collection, motoneurons that had reinnervated SOL and TA were labeled retrogradely. Putative primary afferent terminals [i.e., terminals containing vesicular glutamate transporter-1 (VGLUT1)] on SOL motoneurons were studied immunohistochemically. SOL (and probably TA) background EMG activity recovered faster in TU rats than in TC rats, and the final recovered SOL H-reflex was significantly larger in TU than in TC rats. TU and TC rats had significantly fewer labeled motoneurons and higher proportions of double-labeled motoneurons than untransected rats. VGLUT1 terminals were significantly more numerous on SOL motoneurons of TU than TC rats. Combined with the larger H-reflexes in TU rats, this anatomical finding supports the hypothesis that SOL H-reflex up-conditioning strengthened primary afferent reinnervation of SOL motoneurons. These results suggest that H-reflex up-conditioning may improve functional recovery after nerve injury and repair.}, keywords = {conditioning, peripheral nerve, plasticity, Reflex, regeneration, Spinal Cord}, issn = {1529-2401}, doi = {10.1523/JNEUROSCI.4578-10.2010}, url = {http://www.ncbi.nlm.nih.gov/pubmed/21123559}, author = {Yi Chen and Wang, Yu and Lu Chen and Sun, Chenyou and English, Arthur W. and Jonathan Wolpaw and Xiang Yang Chen} } @article {3104, title = {A novel P300-based brain-computer interface stimulus presentation paradigm: moving beyond rows and columns.}, journal = {Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology}, volume = {121}, year = {2010}, month = {07/2010}, pages = {1109{\textendash}1120}, abstract = {OBJECTIVE: An electroencephalographic brain-computer interface (BCI) can provide a non-muscular means of communication for people with amyotrophic lateral sclerosis (ALS) or other neuromuscular disorders. We present a novel P300-based BCI stimulus presentation - the checkerboard paradigm (CBP). CBP performance is compared to that of the standard row/column paradigm (RCP) introduced by Farwell and Donchin (1988). METHODS: Using an 8x9 matrix of alphanumeric characters and keyboard commands, 18 participants used the CBP and RCP in counter-balanced fashion. With approximately 9-12 min of calibration data, we used a stepwise linear discriminant analysis for online classification of subsequent data. RESULTS: Mean online accuracy was significantly higher for the CBP, 92\%, than for the RCP, 77\%. Correcting for extra selections due to errors, mean bit rate was also significantly higher for the CBP, 23 bits/min, than for the RCP, 17 bits/min. Moreover, the two paradigms produced significantly different waveforms. Initial tests with three advanced ALS participants produced similar results. Furthermore, these individuals preferred the CBP to the RCP. CONCLUSIONS: These results suggest that the CBP is markedly superior to the RCP in performance and user acceptability. SIGNIFICANCE: The CBP has the potential to provide a substantially more effective BCI than the RCP. This is especially important for people with severe neuromuscular disabilities.}, keywords = {brain-computer interface, brain-machine interface, EEG, event-related potential, P300, Rehabilitation}, issn = {1872-8952}, doi = {10.1016/j.clinph.2010.01.030}, url = {http://www.ncbi.nlm.nih.gov/pubmed/20347387}, author = {Townsend, G. and LaPallo, B. K. and Chadwick B. Boulay and Krusienski, D. J. and Frye, G. E. and Hauser, C. K. and Schwartz, N. E. and Theresa M Vaughan and Jonathan Wolpaw and Sellers, E. W.} } @article {3100, title = {Reflex conditioning: a new strategy for improving motor function after spinal cord injury.}, journal = {Annals of the New York Academy of Sciences}, volume = {1198 Suppl 1}, year = {2010}, month = {06/2010}, pages = {E12{\textendash}E21}, abstract = {Spinal reflex conditioning changes reflex size, induces spinal cord plasticity, and modifies locomotion. Appropriate reflex conditioning can improve walking in rats after spinal cord injury (SCI). Reflex conditioning offers a new therapeutic strategy for restoring function in people with SCI. This approach can address the specific deficits of individuals with SCI by targeting specific reflex pathways for increased or decreased responsiveness. In addition, once clinically significant regeneration can be achieved, reflex conditioning could provide a means of reeducating the newly (and probably imperfectly) reconnected spinal cord.}, keywords = {H-Reflex, learning and memory, Locomotion, plasticity, reflex conditioning, Rehabilitation, spinal cord injury}, issn = {1749-6632}, doi = {10.1111/j.1749-6632.2010.05565.x}, url = {http://www.ncbi.nlm.nih.gov/pubmed/20590534}, author = {Xiang Yang Chen and Yi Chen and Wang, Yu and Thompson, Aiko and Jonathan S. Carp and Segal, Richard L. and Jonathan Wolpaw} } @article {3098, title = {What can the spinal cord teach us about learning and memory?.}, journal = {The Neuroscientist : a review journal bringing neurobiology, neurology and psychiatry}, volume = {16}, year = {2010}, month = {10/2010}, pages = {532{\textendash}549}, abstract = {The work of recent decades has shown that the nervous system changes continually throughout life. Activity-dependent central nervous system (CNS) plasticity has many different mechanisms and involves essentially every region, from the cortex to the spinal cord. This new knowledge radically changes the challenge of explaining learning and memory and greatly increases the relevance of the spinal cord. The challenge is now to explain how continual and ubiquitous plasticity accounts for the initial acquisition and subsequent stability of many different learned behaviors. The spinal cord has a key role because it is the final common pathway for all behavior and is a site of substantial plasticity. Furthermore, because it is simple, accessible, distant from the rest of the CNS, and directly connected to behavior, the spinal cord is uniquely suited for identifying sites and mechanisms of plasticity and for determining how they account for behavioral change. Experimental models based on spinal cord reflexes facilitate study of the gradual plasticity that makes possible most rapid learning phenomena. These models reveal principles and generate concepts that are likely to apply to learning and memory throughout the CNS. In addition, they offer new approaches to guiding activity-dependent plasticity so as to restore functions lost to injury or disease.}, keywords = {Spinal Cord}, issn = {1089-4098}, doi = {10.1177/1073858410368314}, url = {http://www.ncbi.nlm.nih.gov/pubmed/20889964}, author = {Jonathan Wolpaw} } @article {3109, title = {Acquisition of a simple motor skill: task-dependent adaptation plus long-term change in the human soleus H-reflex.}, journal = {The Journal of neuroscience : the official journal of the Society for Neuroscience}, volume = {29}, year = {2009}, month = {05/2009}, pages = {5784{\textendash}5792}, abstract = {Activity-dependent plasticity occurs throughout the CNS. However, investigations of skill acquisition usually focus on cortex. To expand the focus, we analyzed in humans the development of operantly conditioned H-reflex change, a simple motor skill that develops gradually and involves plasticity in both the brain and the spinal cord. Each person completed 6 baseline and 24 conditioning sessions over 10 weeks. In each conditioning session, the soleus H-reflex was measured while the subject was or was not asked to increase (HRup subjects) or decrease (HRdown subjects) it. When the subject was asked to change H-reflex size, immediate visual feedback indicated whether a size criterion had been satisfied. Over the 24 conditioning sessions, H-reflex size gradually increased in six of eight HRup subjects and decreased in eight of nine HRdown subjects, resulting in final sizes of 140 +/- 12 and 69 +/- 6\% of baseline size, respectively. The final H-reflex change was the sum of within-session (i.e., task-dependent) adaptation and across-session (i.e., long-term) change. Task-dependent adaptation appeared within four to six sessions and persisted thereafter, averaging +13\% in HRup subjects and -15\% in HRdown subjects. In contrast, long-term change began after 10 sessions and increased gradually thereafter, reaching +27\% in HRup subjects and -16\% in HRdown subjects. Thus, the acquisition of H-reflex conditioning consists of two phenomena, task-dependent adaptation and long-term change, that together constitute the new motor skill. In combination with previous data, this new finding further elucidates the interaction of plasticity in brain and spinal cord that underlies the acquisition and maintenance of motor skills.}, keywords = {H-Reflex, motor learning, motor skill, operant conditioning, plasticity, Spinal Cord}, issn = {1529-2401}, doi = {10.1523/JNEUROSCI.4326-08.2009}, url = {http://www.ncbi.nlm.nih.gov/pubmed/19420246}, author = {Thompson, Aiko K. and Xiang Yang Chen and Jonathan Wolpaw} } @article {3107, title = {Brain-computer interface research at the wadsworth center developments in noninvasive communication and control.}, journal = {International review of neurobiology}, volume = {86}, year = {2009}, month = {02/2009}, pages = {147{\textendash}157}, abstract = {Brain-computer interface (BCI) research at the Wadsworth Center focuses on noninvasive, electroencephalography (EEG)-based BCI methods for helping severely disabled individuals communicate and interact with their environment. We have demonstrated that these individuals, as well as able-bodied individuals, can learn to use sensorimotor rhythms (SMRs) to move a cursor rapidly and accurately in one and two dimensions. We have also developed a practical P300-based BCI that enables users to access and control the full functionality of their personal computer. We are currently translating this laboratory-proved BCI technology into a system that can be used by severely disabled individuals in their homes with minimal ongoing technical oversight. Our comprehensive approach to BCI design has led to several innovations that are applicable in other BCI contexts, such as space missions.}, keywords = {User-Computer Interface}, issn = {0074-7742}, doi = {10.1016/S0074-7742(09)86011-X}, url = {http://www.ncbi.nlm.nih.gov/pubmed/19607997}, author = {Krusienski, Dean J. and Jonathan Wolpaw} } @article {3111, title = {Clinical Applications of Brain-Computer Interfaces: Current State and Future Prospects.}, journal = {IEEE reviews in biomedical engineering}, volume = {2}, year = {2009}, month = {2009}, pages = {187{\textendash}199}, abstract = {Brain-computer interfaces (BCIs) allow their users to communicate or control external devices using brain signals rather than the brain{\textquoteright}s normal output pathways of peripheral nerves and muscles. Motivated by the hope of restoring independence to severely disabled individuals and by interest in further extending human control of external systems, researchers from many fields are engaged in this challenging new work. BCI research and development have grown explosively over the past two decades. Efforts have recently begun to provide laboratory-validated BCI systems to severely disabled individuals for real-world applications. In this review, we discuss the current status and future prospects of BCI technology and its clinical applications. We will define BCI, review the BCI-relevant signals from the human brain, and describe the functional components of BCIs. We will also review current clinical applications of BCI technology, and identify potential users and potential applications. Finally, we will discuss current limitations of BCI technology, impediments to its widespread clinical use, and expectations for the future.}, issn = {1941-1189}, doi = {10.1109/RBME.2009.2035356}, url = {http://www.ncbi.nlm.nih.gov/pubmed/20442804}, author = {Mak, Joseph N. and Jonathan Wolpaw} } @article {2193, title = {Decoding flexion of individual fingers using electrocorticographic signals in humans.}, journal = {J Neural Eng}, volume = {6}, year = {2009}, month = {12/2009}, pages = {066001}, abstract = {

Brain signals can provide the basis for a non-muscular communication and control system, a brain-computer interface (BCI), for people with motor disabilities. A common approach to creating BCI devices is to decode kinematic parameters of movements using signals recorded by intracortical microelectrodes. Recent studies have shown that kinematic parameters of hand movements can also be accurately decoded from signals recorded by electrodes placed on the surface of the brain (electrocorticography (ECoG)). In the present study, we extend these results by demonstrating that it is also possible to decode the time course of the flexion of individual fingers using ECoG signals in humans, and by showing that these flexion time courses are highly specific to the moving finger. These results provide additional support for the hypothesis that ECoG could be the basis for powerful clinically practical BCI systems, and also indicate that ECoG is useful for studying cortical dynamics related to motor function.

}, keywords = {Adolescent, Adult, Biomechanics, Brain, Electrodiagnosis, Epilepsy, Female, Fingers, Humans, Male, Microelectrodes, Middle Aged, Motor Activity, Rest, Thumb, Time Factors, Young Adult}, issn = {1741-2552}, doi = {10.1088/1741-2560/6/6/066001}, url = {http://www.ncbi.nlm.nih.gov/pubmed/19794237}, author = {Kub{\'a}nek, J and Miller, John W and Ojemann, J G and Jonathan Wolpaw and Gerwin Schalk} } @article {3110, title = {H-reflex down-conditioning greatly increases the number of identifiable GABAergic interneurons in rat ventral horn.}, journal = {Neuroscience letters}, volume = {452}, year = {2009}, month = {03/2009}, pages = {124{\textendash}129}, abstract = {H-reflex down-conditioning increases GABAergic terminals on spinal cord motoneurons. To explore the origins of these terminals, we studied the numbers and distributions of spinal cord GABAergic interneurons. The number of identifiable GABAergic interneurons in the ventral horn was 78\% greater in rats in which down-conditioning was successful than in naive rats or rats in which down-conditioning failed. No increase occurred in other spinal lamina or on the contralateral side. This finding supports the hypothesis that the corticospinal tract influence that induces the motoneuron plasticity underlying down-conditioning reaches the motoneuron through GABAergic interneurons in the ventral horn.}, keywords = {activity-dependent plasticity, GABAergic interneurons, H-reflex conditioning, learning and memory, Motor control, Spinal Cord}, issn = {0304-3940}, doi = {10.1016/j.neulet.2009.01.054}, url = {http://www.ncbi.nlm.nih.gov/pubmed/19383426}, author = {Wang, Yu and Pillai, Shreejith and Jonathan Wolpaw and Xiang Yang Chen} } @article {3113, title = {A scanning protocol for a sensorimotor rhythm-based brain-computer interface.}, journal = {Biological psychology}, volume = {80}, year = {2009}, month = {02/2009}, pages = {169{\textendash}175}, abstract = {The scanning protocol is a novel brain-computer interface (BCI) implementation that can be controlled with sensorimotor rhythms (SMRs) of the electroencephalogram (EEG). The user views a screen that shows four choices in a linear array with one marked as target. The four choices are successively highlighted for 2.5s each. When a target is highlighted, the user can select it by modulating the SMR. An advantage of this method is the capacity to choose among multiple choices with just one learned SMR modulation. Each of 10 naive users trained for ten 30 min sessions over 5 weeks. User performance improved significantly (p<0.001) over the sessions and ranged from 30 to 80\% mean accuracy of the last three sessions (chance accuracy=25\%). The incidence of correct selections depended on the target position. These results suggest that, with further improvements, a scanning protocol can be effective. The ultimate goal is to expand it to a large matrix of selections.}, keywords = {BCI, brain-computer interface, scanning protocol, sensorimotor rhythm}, issn = {1873-6246}, doi = {10.1016/j.biopsycho.2008.08.004}, url = {http://www.ncbi.nlm.nih.gov/pubmed/18786603}, author = {Friedrich, Elisabeth V. C. and Dennis J. McFarland and Neuper, Christa and Theresa M Vaughan and Peter Brunner and Jonathan Wolpaw} } @article {3108, title = {Toward a high-throughput auditory P300-based brain-computer interface.}, journal = {Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology}, volume = {120}, year = {2009}, month = {07/2009}, pages = {1252{\textendash}1261}, abstract = {OBJECTIVE: Brain-computer interface (BCI) technology can provide severely disabled people with non-muscular communication. For those most severely disabled, limitations in eye mobility or visual acuity may necessitate auditory BCI systems. The present study investigates the efficacy of the use of six environmental sounds to operate a 6x6 P300 Speller. METHODS: A two-group design was used to ascertain whether participants benefited from visual cues early in training. Group A (N=5) received only auditory stimuli during all 11 sessions, whereas Group AV (N=5) received simultaneous auditory and visual stimuli in initial sessions after which the visual stimuli were systematically removed. Stepwise linear discriminant analysis determined the matrix item that elicited the largest P300 response and thereby identified the desired choice. RESULTS: Online results and offline analyses showed that the two groups achieved equivalent accuracy. In the last session, eight of 10 participants achieved 50\% or more, and four of these achieved 75\% or more, online accuracy (2.8\% accuracy expected by chance). Mean bit rates averaged about 2 bits/min, and maximum bit rates reached 5.6 bits/min. CONCLUSIONS: This study indicates that an auditory P300 BCI is feasible, that reasonable classification accuracy and rate of communication are achievable, and that the paradigm should be further evaluated with a group of severely disabled participants who have limited visual mobility. SIGNIFICANCE: With further development, this auditory P300 BCI could be of substantial value to severely disabled people who cannot use a visual BCI.}, keywords = {brain-computer interface, brain-machine interface, EEG, event-related potential, P300, Rehabilitation}, issn = {1872-8952}, doi = {10.1016/j.clinph.2009.04.019}, url = {http://www.ncbi.nlm.nih.gov/pubmed/19574091}, author = {Klobassa, D. S. and Theresa M Vaughan and Peter Brunner and Schwartz, N. E. and Jonathan Wolpaw and Neuper, C. and Sellers, E. W.} } @article {2183, title = {Brain-computer interfaces (BCIs): Detection Instead of Classification.}, journal = {J Neurosci Methods}, volume = {167}, year = {2008}, month = {01/2008}, pages = {51-62}, abstract = {

Many studies over the past two decades have shown that people can use\ brain\ signals to convey their intent to a\ computer\ through\ brain-computer interfaces\ (BCIs). These devices operate by recording signals from the\ brain\ and translating these signals into device commands. They can be used by people who are severely paralyzed to communicate without any use of muscle activity. One of the major impediments in translating this novel technology into\ clinical\ applications is the current requirement for preliminary analyses to identify the\ brain\ signal features best suited for communication. This paper introduces and validates signal detection, which does not require such analysis procedures, as a new concept in BCI signal processing. This detection concept is realized with Gaussian mixture models (GMMs) that are used to model resting\ brain\ activity so that any change in\ relevantbrain\ signals can be detected. It is implemented in a package called SIGFRIED (SIGnal modeling For Real-time Identification and Event Detection). The results indicate that SIGFRIED produces results that are within the range of those achieved using a common analysis strategy that requires preliminary identification of signal features. They indicate that such laborious analysis procedures could be replaced by merely recording\ brain\ signals during rest. In summary, this paper demonstrates how SIGFRIED could be used to overcome one of the present impediments to translation of laboratory BCI demonstrations into clinically practical applications.

}, keywords = {Adult, Algorithms, Brain, Brain Mapping, Electrocardiography, Electroencephalography, Humans, Male, Man-Machine Systems, Normal Distribution, Online Systems, Signal Detection, Psychological, Signal Processing, Computer-Assisted, Software Validation, User-Computer Interface}, issn = {0165-0270}, doi = {10.1016/j.jneumeth.2007.08.010}, url = {http://www.ncbi.nlm.nih.gov/pubmed/17920134}, author = {Gerwin Schalk and Peter Brunner and Lester A Gerhardt and H Bischof and Jonathan Wolpaw} } @article {3112, title = {Brain-computer interfaces in neurological rehabilitation.}, journal = {Lancet neurology}, volume = {7}, year = {2008}, month = {11/2008}, pages = {1032{\textendash}1043}, abstract = {Recent advances in analysis of brain signals, training patients to control these signals, and improved computing capabilities have enabled people with severe motor disabilities to use their brain signals for communication and control of objects in their environment, thereby bypassing their impaired neuromuscular system. Non-invasive, electroencephalogram (EEG)-based brain-computer interface (BCI) technologies can be used to control a computer cursor or a limb orthosis, for word processing and accessing the internet, and for other functions such as environmental control or entertainment. By re-establishing some independence, BCI technologies can substantially improve the lives of people with devastating neurological disorders such as advanced amyotrophic lateral sclerosis. BCI technology might also restore more effective motor control to people after stroke or other traumatic brain disorders by helping to guide activity-dependent brain plasticity by use of EEG brain signals to indicate to the patient the current state of brain activity and to enable the user to subsequently lower abnormal activity. Alternatively, by use of brain signals to supplement impaired muscle control, BCIs might increase the efficacy of a rehabilitation protocol and thus improve muscle control for the patient.}, keywords = {User-Computer Interface}, issn = {1474-4422}, doi = {10.1016/S1474-4422(08)70223-0}, url = {http://www.ncbi.nlm.nih.gov/pubmed/18835541}, author = {Janis J. Daly and Jonathan Wolpaw} } @article {3188, title = {Effects of H-reflex up-conditioning on GABAergic terminals on rat soleus motoneurons.}, journal = {The European journal of neuroscience}, volume = {28}, year = {2008}, month = {08/2008}, pages = {668{\textendash}674}, abstract = {To explore the role of spinal cord plasticity in motor learning, we evaluated the effects of H-reflex operant conditioning on GABAergic input to rat spinal motoneurons. Previous work indicated that down-conditioning of soleus H-reflex increases GABAergic input to soleus motoneurons. This study explored the effect of H-reflex up-conditioning on GABAergic input. Of nine rats exposed to H-reflex up-conditioning, up-conditioning was successful (H-reflex increase >or= 20\%) in seven and failed (change < 20\%) in two. These rats and eight naive control (i.e. unconditioned) rats were injected with cholera toxin subunit B-conjugated Alexa fluor 488 into the soleus muscle to retrogradely label soleus motoneurons. Sections containing soleus motoneurons were processed for GAD(67) [one of the two principal forms of the GABA-synthesizing enzyme glutamic acid decarboxylase (GAD)] with an ABC-peroxidase system. Two blinded independent raters counted and measured GABAergic terminals on these motoneurons. Unlike successful down-conditioning, which greatly increased the number of identifiable GABAergic terminals on the motoneurons, up-conditioning did not significantly change GABAergic terminal number. Successful up-conditioning did produce slight but statistically significant increases in GABAergic terminal diameter and soma coverage. These results are consistent with other data indicating that up- and down-conditioning are not mirror images of each other, but rather have different mechanisms. Although the marked changes in GABAergic terminals with down-conditioning probably contribute to H-reflex decrease, the modest changes in GABAergic terminals associated with up-conditioning may be compensatory or reactive plasticity, rather than the plasticity responsible for H-reflex increase. As a variety of spinal and supraspinal GABAergic neurons innervate motoneurons, the changes found with up-conditioning may be in terminals other than those affected in successful down-conditioning.}, keywords = {activity-dependent plasticity, Learning, Memory, Motor control, Spinal Cord}, issn = {1460-9568}, doi = {10.1111/j.1460-9568.2008.06370.x}, url = {http://www.ncbi.nlm.nih.gov/pubmed/18657184}, author = {Pillai, Shreejith and Wang, Yu and Jonathan Wolpaw and Xiang Yang Chen} } @article {3131, title = {Emulation of computer mouse control with a noninvasive brain-computer interface.}, journal = {Journal of neural engineering}, volume = {5}, year = {2008}, month = {06/2008}, pages = {101{\textendash}110}, abstract = {Brain-computer interface (BCI) technology can provide nonmuscular communication and control to people who are severely paralyzed. BCIs can use noninvasive or invasive techniques for recording the brain signals that convey the user{\textquoteright}s commands. Although noninvasive BCIs are used for simple applications, it has frequently been assumed that only invasive BCIs, which use electrodes implanted in the brain, will be able to provide multidimensional sequential control of a robotic arm or a neuroprosthesis. The present study shows that a noninvasive BCI using scalp-recorded electroencephalographic (EEG) activity and an adaptive algorithm can provide people, including people with spinal cord injuries, with two-dimensional cursor movement and target selection. Multiple targets were presented around the periphery of a computer screen, with one designated as the correct target. The user{\textquoteright}s task was to use EEG to move a cursor from the center of the screen to the correct target and then to use an additional EEG feature to select the target. If the cursor reached an incorrect target, the user was instructed not to select it. Thus, this task emulated the key features of mouse operation. The results indicate that people with severe motor disabilities could use brain signals for sequential multidimensional movement and selection.}, keywords = {User-Computer Interface}, issn = {1741-2560}, doi = {10.1088/1741-2560/5/2/001}, url = {http://www.ncbi.nlm.nih.gov/pubmed/18367779}, author = {Dennis J. McFarland and Krusienski, Dean J. and Sarnacki, William A. and Jonathan Wolpaw} } @article {3149, title = {An in vitro protocol for recording from spinal motoneurons of adult rats.}, journal = {Journal of neurophysiology}, volume = {100}, year = {2008}, month = {07/2008}, pages = {474{\textendash}481}, abstract = {In vitro slice preparations of CNS tissue are invaluable for studying neuronal function. However, up to now, slice protocols for adult mammal spinal motoneurons{\textendash}the final common pathway for motor behaviors{\textendash}have been available for only limited portions of the spinal cord. In most cases, these preparations have not been productive due to the poor viability of motoneurons in vitro. This report describes and validates a new slice protocol that for the first time provides reliable intracellular recordings from lumbar motoneurons of adult rats. The key features of this protocol are: preexposure to 100\% oxygen; laminectomy prior to perfusion; anesthesia with ketamine/xylazine; embedding the spinal cord in agar prior to slicing; and, most important, brief incubation of spinal cord slices in a 30\% solution of polyethylene glycol to promote resealing of the many motoneuron dendrites cut during sectioning. Together, these new features produce successful recordings in 76\% of the experiments and an average action potential amplitude of 76 mV. Motoneuron properties measured in this new slice preparation (i.e., voltage and current thresholds for action potential initiation, input resistance, afterhyperpolarization size and duration, and onset and offset firing rates during current ramps) are comparable to those recorded in vivo. Given the mechanical stability and precise control over the extracellular environment afforded by an in vitro preparation, this new protocol can greatly facilitate electrophysiological and pharmacological study of these uniquely important neurons and other delicate neuronal populations in adult mammals.}, keywords = {Tissue and Organ Harvesting}, issn = {0022-3077}, doi = {10.1152/jn.90422.2008}, url = {http://www.ncbi.nlm.nih.gov/pubmed/18463177}, author = {Jonathan S. Carp and Tennissen, Ann M. and Mongeluzi, Donna L. and Dudek, Christopher J. and Xiang Yang Chen and Jonathan Wolpaw} } @article {3199, title = {A P300-based brain-computer interface for people with amyotrophic lateral sclerosis.}, journal = {Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology}, volume = {119}, year = {2008}, month = {08/2008}, pages = {1909{\textendash}1916}, abstract = {OBJECTIVE: The current study evaluates the efficacy of a P300-based brain-computer interface (BCI) communication device for individuals with advanced ALS. METHODS: Participants attended to one cell of a N x N matrix while the N rows and N columns flashed randomly. Each cell of the matrix contained one character. Every flash of an attended character served as a rare event in an oddball sequence and elicited a P300 response. Classification coefficients derived using a stepwise linear discriminant function were applied to the data after each set of flashes. The character receiving the highest discriminant score was presented as feedback. RESULTS: In Phase I, six participants used a 6 x 6 matrix on 12 separate days with a mean rate of 1.2 selections/min and mean online and offline accuracies of 62\% and 82\%, respectively. In Phase II, four participants used either a 6 x 6 or a 7 x 7 matrix to produce novel and spontaneous statements with a mean online rate of 2.1 selections/min and online accuracy of 79\%. The amplitude and latency of the P300 remained stable over 40 weeks. CONCLUSIONS: Participants could communicate with the P300-based BCI and performance was stable over many months. SIGNIFICANCE: BCIs could provide an alternative communication and control technology in the daily lives of people severely disabled by ALS.}, keywords = {Amyotrophic Lateral Sclerosis, brain-computer interface, electroencephalogram, event-related potentials, P300, Rehabilitation}, issn = {1388-2457}, doi = {10.1016/j.clinph.2008.03.034}, url = {http://www.ncbi.nlm.nih.gov/pubmed/18571984}, author = {Nijboer, F. and Sellers, E. W. and Mellinger, J. and Jordan, M. A. and Matuz, T. and Adrian Furdea and S Halder and Mochty, U. and Krusienski, D. J. and Theresa M Vaughan and Jonathan Wolpaw and Niels Birbaumer and K{\"u}bler, A.} } @article {2187, title = {Real-time detection of event-related brain activity.}, journal = {Neuroimage}, volume = {43}, year = {2008}, month = {11/2008}, pages = {245-9}, abstract = {

The complexity and inter-individual variation of\ brain\ signals impedes real-time detection of events in raw signals. To convert these complex signals into results that can be readily understood, current approaches usually apply statistical methods to data from known conditions after all data have been collected. The capability to provide meaningful visualization of complex\ brain\ signals without the requirement to initially collect data from all conditions would provide a new tool, essentially a new imaging technique, that would open up new avenues for the study of\ brain\ function. Here we show that a new analysis approach, called SIGFRIED, can overcome this serious limitation of current methods. SIGFRIED can visualize\ brain\ signal changes without requiring prior data collection from all conditions. This capacity is particularly well suited to applications in which comprehensive prior data collection is impossible or impractical, such as intraoperative localization of cortical function or detection of epileptic seizures.

}, keywords = {Adult, Algorithms, Brain Mapping, Computer Systems, Diagnosis, Computer-Assisted, Electroencephalography, Epilepsy, Evoked Potentials, Female, Humans, Male, Pattern Recognition, Automated, Reproducibility of Results, Sensitivity and Specificity}, issn = {1095-9572}, doi = {10.1016/j.neuroimage.2008.07.037}, url = {http://www.ncbi.nlm.nih.gov/pubmed/18718544}, author = {Gerwin Schalk and Leuthardt, E C and Peter Brunner and Ojemann, J G and Lester A Gerhardt and Jonathan Wolpaw} } @article {3129, title = {Sensorimotor rhythm-based brain-computer interface (BCI): model order selection for autoregressive spectral analysis.}, journal = {Journal of neural engineering}, volume = {5}, year = {2008}, month = {06/2008}, pages = {155{\textendash}162}, abstract = {People can learn to control EEG features consisting of sensorimotor rhythm amplitudes and can use this control to move a cursor in one or two dimensions to a target on a screen. Cursor movement depends on the estimate of the amplitudes of sensorimotor rhythms. Autoregressive models are often used to provide these estimates. The order of the autoregressive model has varied widely among studies. Through analyses of both simulated and actual EEG data, the present study examines the effects of model order on sensorimotor rhythm measurements and BCI performance. The results show that resolution of lower frequency signals requires higher model orders and that this requirement reflects the temporal span of the model coefficients. This is true for both simulated EEG data and actual EEG data during brain-computer interface (BCI) operation. Increasing model order, and decimating the signal were similarly effective in increasing spectral resolution. Furthermore, for BCI control of two-dimensional cursor movement, higher model orders produced better performance in each dimension and greater independence between horizontal and vertical movements. In sum, these results show that autoregressive model order selection is an important determinant of BCI performance and should be based on criteria that reflect system performance.}, keywords = {User-Computer Interface}, issn = {1741-2560}, doi = {10.1088/1741-2560/5/2/006}, url = {http://www.ncbi.nlm.nih.gov/pubmed/18430974}, author = {Dennis J. McFarland and Jonathan Wolpaw} } @article {3205, title = {Toward enhanced P300 speller performance.}, journal = {Journal of neuroscience methods}, volume = {167}, year = {2008}, month = {01/2008}, pages = {15{\textendash}21}, abstract = {This study examines the effects of expanding the classical P300 feature space on the classification performance of data collected from a P300 speller paradigm [Farwell LA, Donchin E. Talking off the top of your head: toward a mental prosthesis utilizing event-related brain potentials. Electroenceph Clin Neurophysiol 1988;70:510-23]. Using stepwise linear discriminant analysis (SWLDA) to construct a classifier, the effects of spatial channel selection, channel referencing, data decimation, and maximum number of model features are compared with the intent of establishing a baseline not only for the SWLDA classifier, but for related P300 speller classification methods in general. By supplementing the classical P300 recording locations with posterior locations, online classification performance of P300 speller responses can be significantly improved using SWLDA and the favorable parameters derived from the offline comparative analysis.}, keywords = {brain-computer interface, event related potentials, P300 speller, stepwise linear discriminant analysis}, issn = {0165-0270}, doi = {10.1016/j.jneumeth.2007.07.017}, url = {http://www.ncbi.nlm.nih.gov/pubmed/17822777}, author = {Krusienski, D. J. and Sellers, E. W. and Dennis J. McFarland and Theresa M Vaughan and Jonathan Wolpaw} } @article {2184, title = {Towards an independent brain-computer interface using steady state visual evoked potentials.}, journal = {Clin Neurophysiol}, volume = {119}, year = {2008}, month = {02/2008}, pages = {399-408}, abstract = {

OBJECTIVE:\ 

Brain-computer interface (BCI) systems using steady state visual evoked potentials (SSVEPs) have allowed healthy subjects to communicate. However, these systems may not work in severely disabled users because they may depend on gaze shifting. This study evaluates the hypothesis that overlapping stimuli can evoke changes in SSVEP activity sufficient to control a BCI. This would provide evidence that SSVEP BCIs could be used without shifting gaze.

METHODS:\ 

Subjects viewed a display containing two images that each oscillated at a different frequency. Different conditions used overlapping or non-overlapping images to explore dependence on gaze function. Subjects were asked to direct attention to one or the other of these images during each of 12 one-minute runs.

RESULTS:\ 

Half of the subjects produced differences in SSVEP activity elicited by overlapping stimuli that could support BCI control. In all remaining users, differences did exist at corresponding frequencies but were not strong enough to allow effective control.

CONCLUSIONS:\ 

The\ data\ demonstrate that SSVEP differences sufficient for BCI control may be elicited by selective attention to one of two overlapping stimuli. Thus, some SSVEP-based BCI approaches may not depend on gaze control. The nature and extent of any BCI{\textquoteright}s dependence on muscle activity is a function of many factors, including the display, task, environment, and user.

SIGNIFICANCE:\ 

SSVEP BCIs might function in severely disabled users unable to reliably control gaze. Further research with these users is necessary to explore the optimal parameters of such a system and validate online performance in a home environment.

}, keywords = {Adolescent, Adult, Attention, Brain, Brain Mapping, Dose-Response Relationship, Radiation, Electroencephalography, Evoked Potentials, Visual, Female, Humans, Male, Pattern Recognition, Visual, Photic Stimulation, Spectrum Analysis, User-Computer Interface}, issn = {1388-2457}, doi = {10.1016/j.clinph.2007.09.121}, url = {http://www.ncbi.nlm.nih.gov/pubmed/18077208}, author = {Brendan Z. Allison and Dennis J. McFarland and Gerwin Schalk and Zheng, Shi Dong and Moore-Jackson, Melody and Jonathan Wolpaw} } @article {2186, title = {Two-dimensional movement control using electrocorticographic signals in humans.}, journal = {J Neural Eng}, volume = {5}, year = {2008}, month = {03/2008}, pages = {75-84}, abstract = {

We show here that a\ brain-computer\ interface (BCI) using electrocorticographic activity (ECoG) and imagined or overt motor tasks enables humans to control a\ computer\ cursor in two dimensions. Over a brief training period of 12-36 min, each of five human subjects acquired substantial control of particular ECoG features recorded from several locations over the same hemisphere, and achieved average success rates of 53-73\% in a two-dimensional four-target center-out task in which chance accuracy was 25\%. Our results support the expectation that ECoG-based BCIs can combine high performance with technical and\ clinical\ practicality, and also indicate promising directions for further research.

}, keywords = {Adolescent, Adult, Brain Mapping, Data Interpretation, Statistical, Drug Resistance, Electrocardiography, Electrodes, Implanted, Electroencephalography, Epilepsy, Female, Humans, Male, Movement, User-Computer Interface}, issn = {1741-2560}, doi = {10.1088/1741-2560/5/1/008}, url = {http://www.ncbi.nlm.nih.gov/pubmed/18310813}, author = {Gerwin Schalk and Miller, K.J. and Nicholas R Anderson and Adam J Wilson and Smyth, Matt and Ojemann, J G and Moran, D and Jonathan Wolpaw and Leuthardt, E C} } @article {3207, title = {Brain-computer interface systems: progress and prospects.}, journal = {Expert review of medical devices}, volume = {4}, year = {2007}, month = {07/2007}, pages = {463{\textendash}474}, abstract = {Brain-computer interface (BCI) systems support communication through direct measures of neural activity without muscle activity. BCIs may provide the best and sometimes the only communication option for users disabled by the most severe neuromuscular disorders and may eventually become useful to less severely disabled and/or healthy individuals across a wide range of applications. This review discusses the structure and functions of BCI systems, clarifies terminology and addresses practical applications. Progress and opportunities in the field are also identified and explicated.}, keywords = {ALS, assistive communication, BCI, BMI, brain-acuated control, brain-computer interface, brain-machine interface, EEG, ERP, locked-in syndrome, slow cortical potential, SSVEP, Stroke}, issn = {1743-4440}, doi = {10.1586/17434440.4.4.463}, url = {http://www.ncbi.nlm.nih.gov/pubmed/17605682}, author = {Brendan Z. Allison and Wolpaw, Elizabeth Winter and Jonathan Wolpaw} } @article {3209, title = {Brain-computer interfaces as new brain output pathways.}, journal = {The Journal of physiology}, volume = {579}, year = {2007}, month = {03/2007}, pages = {613{\textendash}619}, abstract = {Brain-computer interfaces (BCIs) can provide non-muscular communication and control for people with severe motor disabilities. Current BCIs use a variety of invasive and non-invasive methods to record brain signals and a variety of signal processing methods. Whatever the recording and processing methods used, BCI performance (e.g. the ability of a BCI to control movement of a computer cursor) is highly variable and, by the standards applied to neuromuscular control, could be described as ataxic. In an effort to understand this imperfection, this paper discusses the relevance of two principles that underlie the brain{\textquoteright}s normal motor outputs. The first principle is that motor outputs are normally produced by the combined activity of many CNS areas, from the cortex to the spinal cord. Together, these areas produce appropriate control of the spinal motoneurons that activate muscles. The second principle is that the acquisition and life-long preservation of motor skills depends on continual adaptive plasticity throughout the CNS. This plasticity optimizes the control of spinal motoneurons. In the light of these two principles, a BCI may be viewed as a system that changes the outcome of CNS activity from control of spinal motoneurons to, instead, control of the cortical (or other) area whose signals are used by the BCI to determine the user{\textquoteright}s intent. In essence, a BCI attempts to assign to cortical neurons the role normally performed by spinal motoneurons. Thus, a BCI requires that the many CNS areas involved in producing normal motor actions change their roles so as to optimize the control of cortical neurons rather than spinal motoneurons. The disconcerting variability of BCI performance may stem in large part from the challenge presented by the need for this unnatural adaptation. This difficulty might be reduced, and BCI development might thereby benefit, by adopting a {\textquoteright}goal-selection{\textquoteright} rather than a {\textquoteright}process- control{\textquoteright} strategy. In {\textquoteright}process control{\textquoteright}, a BCI manages all the intricate high-speed interactions involved in movement. In {\textquoteright}goal selection{\textquoteright}, by contrast, the BCI simply communicates the user{\textquoteright}s goal to software that handles the high-speed interactions needed to achieve the goal. Not only is {\textquoteright}goal selection{\textquoteright} less demanding, but also, by delegating lower-level aspects of motor control to another structure (rather than requiring that the cortex do everything), it more closely resembles the distributed operation characteristic of normal motor control.}, keywords = {User-Computer Interface}, issn = {0022-3751}, doi = {10.1113/jphysiol.2006.125948}, url = {http://www.ncbi.nlm.nih.gov/pubmed/17255164}, author = {Jonathan Wolpaw} } @article {2182, title = {Decoding two-dimensional movement trajectories using electrocorticographic signals in humans.}, journal = {J Neural Eng}, volume = {4}, year = {2007}, month = {09/2007}, pages = {264-75}, abstract = {

Signals from the brain could provide a non-muscular communication and control system, a brain-computer interface (BCI), for people who are severely paralyzed. A common BCI research strategy begins by decoding kinematic parameters from brain signals recorded during actual arm movement. It has been assumed that these parameters can be derived accurately only from signals recorded by intracortical microelectrodes, but the long-term stability of such electrodes is uncertain. The present study disproves this widespread assumption by showing in humans that kinematic parameters can also be decoded from signals recorded by subdural electrodes on the cortical surface (ECoG) with an accuracy comparable to that achieved in monkey studies using intracortical microelectrodes. A new ECoG feature labeled the local motor potential (LMP) provided the most information about movement. Furthermore, features displayed cosine tuning that has previously been described only for signals recorded within the brain. These results suggest that ECoG could be a more stable and less invasive alternative to intracortical electrodes for BCI systems, and could also prove useful in studies of motor function.

}, keywords = {Adult, Algorithms, Arm, Brain Mapping, Cerebral Cortex, Electroencephalography, Evoked Potentials, Motor, Female, Humans, Male, Movement}, issn = {1741-2560}, doi = {10.1088/1741-2560/4/3/012}, url = {http://www.ncbi.nlm.nih.gov/pubmed/17873429}, author = {Gerwin Schalk and Kub{\'a}nek, J and Miller, John W and Nicholas R Anderson and Leuthardt, E C and Ojemann, J G and Limbrick, D and Moran, D and Lester A Gerhardt and Jonathan Wolpaw} } @article {3151, title = {Recovery of electromyographic activity after transection and surgical repair of the rat sciatic nerve.}, journal = {Journal of neurophysiology}, volume = {97}, year = {2007}, month = {02/2007}, pages = {1127{\textendash}1134}, abstract = {The recovery of soleus (SOL), gastrocnemius (GAS), and tibialis anterior (TA) electromyographic activity (EMG) after transection and surgical repair of the sciatic nerve was studied in Sprague-Dawley rats using chronically implanted stimulation and recording electrodes. Spontaneous EMG activity in SOL and GAS and direct muscle (M) responses to posterior tibial nerve stimulation persisted for < or =2 days after sciatic nerve transection, but SOL and GAS H-reflexes disappeared immediately. Spontaneous EMG activity began to return 2-3 wk after transection, rose nearly to pretransection levels by 60 days, and persisted for the duration of the study period (120 days). Recovery of stimulus-evoked EMG responses began about 30 days after sciatic nerve transection as multiple small responses with a wide range of latencies. Over time, the latencies of these fractionated responses shortened, their amplitudes increased, and they merged into a distinct short-latency component (the putative M response) and a distinct long-latency component (the putative H-reflex). The extent of recovery of stimulation-evoked EMG was modest: even 100 days after sciatic nerve transection, the responses were still much smaller than those before transection. Similar gradual development of responses to posterior tibial nerve stimulation was also seen in TA, suggesting that some regenerating fibers sent branches into both tibial and common peroneal nerves.}, keywords = {Tibial Nerve}, issn = {0022-3077}, doi = {10.1152/jn.01035.2006}, url = {http://www.ncbi.nlm.nih.gov/pubmed/17122310}, author = {English, Arthur W. and Yi Chen and Jonathan S. Carp and Jonathan Wolpaw and Xiang Yang Chen} } @article {3150, title = {Spinal and supraspinal effects of long-term stimulation of sensorimotor cortex in rats.}, journal = {Journal of neurophysiology}, volume = {98}, year = {2007}, month = {08/2007}, pages = {878{\textendash}887}, abstract = {Sensorimotor cortex (SMC) modifies spinal cord reflex function throughout life and is essential for operant conditioning of the H-reflex. To further explore this long-term SMC influence over spinal cord function and its possible clinical uses, we assessed the effect of long-term SMC stimulation on the soleus H-reflex. In freely moving rats, the soleus H-reflex was measured 24 h/day for 12 wk. The soleus background EMG and M response associated with H-reflex elicitation were kept stable throughout. SMC stimulation was delivered in a 20-day-on/20-day-off/20-day-on protocol in which a train of biphasic 1-ms pulses at 25 Hz for 1 s was delivered every 10 s for the on-days. The SMC stimulus was automatically adjusted to maintain a constant descending volley. H-reflex size gradually increased during the 20 on-days, stayed high during the 20 off-days, and rose further during the next 20 on-days. In addition, the SMC stimulus needed to maintain a stable descending volley rose steadily over days. It fell during the 20 off-days and rose again when stimulation resumed. These results suggest that SMC stimulation, like H-reflex operant conditioning, induces activity-dependent plasticity in both the brain and the spinal cord and that the plasticity responsible for the H-reflex increase persists longer after the end of SMC stimulation than that underlying the change in the SMC response to stimulation.}, keywords = {Time Factors}, issn = {0022-3077}, doi = {10.1152/jn.00283.2007}, url = {http://www.ncbi.nlm.nih.gov/pubmed/17522179}, author = {Xiang Yang Chen and Pillai, Shreejith and Yi Chen and Wang, Yu and Lu Chen and Jonathan S. Carp and Jonathan Wolpaw} } @article {3210, title = {Spinal cord plasticity in acquisition and maintenance of motor skills.}, journal = {Acta physiologica (Oxford, England)}, volume = {189}, year = {2007}, month = {02/2007}, pages = {155{\textendash}169}, abstract = {Throughout normal life, activity-dependent plasticity occurs in the spinal cord as well as in brain. Like other central nervous system (CNS) plasticity, spinal cord plasticity can occur at numerous neuronal and synaptic sites and through a variety of mechanisms. Spinal cord plasticity is prominent early in life and contributes to mastery of standard behaviours like locomotion and rapid withdrawal from pain. Later in life, spinal cord plasticity has a role in acquisition and maintenance of new motor skills, and in compensation for peripheral and central changes accompanying ageing, disease and trauma. Mastery of the simplest behaviours is accompanied by complex spinal and supraspinal plasticity. This complexity is necessary, in order to preserve the complete behavioural repertoire, and is also inevitable, due to the ubiquity of activity-dependent CNS plasticity. Explorations of spinal cord plasticity are necessary for understanding motor skills. Furthermore, the spinal cord{\textquoteright}s comparative simplicity and accessibility makes it a logical starting point for studying skill acquisition. Induction and guidance of activity-dependent spinal cord plasticity will probably play an important role in realization of effective new rehabilitation methods for spinal cord injuries, cerebral palsy and other motor disorders.}, keywords = {conditioning, H-Reflex, Learning, Memory, motor function, plasticity, Rehabilitation, spinal cord injury}, issn = {1748-1708}, doi = {10.1111/j.1748-1716.2006.01656.x}, url = {http://www.ncbi.nlm.nih.gov/pubmed/17250566}, author = {Jonathan Wolpaw} } @article {2174, title = {A {\textmu}-rhythm Matched Filter for Continuous Control of a Brain-Computer Interface.}, journal = {IEEE Trans Biomed Eng}, volume = {54}, year = {2007}, month = {02/2007}, pages = {273-80}, abstract = {

A brain-computer interface (BCI) is a system that provides an alternate nonmuscular communication/control channel for individuals with severe neuromuscular disabilities. With proper training, individuals can learn to modulate the amplitude of specific electroencephalographic (EEG) components (e.g., the 8-12 Hz mu rhythm and 18-26 Hz beta rhythm) over the sensorimotor cortex and use them to control a cursor on a computer screen. Conventional spectral techniques for monitoring the\ continuousamplitude fluctuations fail to capture essential amplitude/phase relationships of the mu and beta rhythms in a compact fashion and, therefore, are suboptimal. By extracting the characteristic mu rhythm for a user, the exact morphology can be characterized and exploited as a matched filter. A simple, parameterized model for the characteristic mu rhythm is proposed and its effectiveness as a matched filter is examined online for a one-dimensional cursor control task. The results suggest that amplitude/phase coupling exists between the mu and beta bands during event-related desynchronization, and that an appropriate matched filter can provide improved performance.

}, keywords = {Algorithms, Cerebral Cortex, Cortical Synchronization, Electroencephalography, Evoked Potentials, Humans, Imagination, Pattern Recognition, Automated, User-Computer Interface}, issn = {0018-9294}, doi = {10.1109/TBME.2006.886661}, url = {http://www.ncbi.nlm.nih.gov/pubmed/17278584}, author = {Krusienski, Dean J and Gerwin Schalk and Dennis J. McFarland and Jonathan Wolpaw} } @article {2172, title = {The BCI competition III: Validating alternative approaches to actual BCI problems.}, journal = {IEEE Trans Neural Syst Rehabil Eng}, volume = {14}, year = {2006}, month = {06/2006}, pages = {153-9}, abstract = {

A\ brain-computer interface\ (BCI) is a system that allows its users to control external devices with\ brainactivity. Although the proof-of-concept was given decades ago, the reliable translation of user intent into device control commands is still a major challenge. Success requires the effective interaction of two adaptive controllers: the user{\textquoteright}s\ brain, which produces\ brain\ activity that encodes intent, and the BCI system, which translates that activity into device control commands. In order to facilitate this interaction, many laboratories are exploring a variety of signal analysis techniques to improve the adaptation of the BCI system to the user. In the literature, many machine learning and pattern classification algorithms have been reported to give impressive results when applied to BCI data in offline analyses. However, it is more difficult to evaluate their relative value for actual\ online\ use. BCI data competitions have been organized to provide objective formal evaluations of alternative methods. Prompted by the great interest in the first two BCI Competitions, we organized the third BCI Competition to address several of the most difficult and important analysis problems in BCI research. The paper describes the data sets that were provided to the competitors and gives an overview of the results.

}, keywords = {Algorithms, Brain, Communication Aids for Disabled, Databases, Factual, Electroencephalography, Evoked Potentials, Humans, Neuromuscular Diseases, Software Validation, Technology Assessment, Biomedical, User-Computer Interface}, issn = {1534-4320}, doi = {10.1109/TNSRE.2006.875642}, url = {http://www.ncbi.nlm.nih.gov/pubmed/16792282}, author = {Benjamin Blankertz and M{\"u}ller, Klaus-Robert and Krusienski, Dean J and Gerwin Schalk and Jonathan Wolpaw and Schl{\"o}gl, Alois and Pfurtscheller, Gert and Mill{\'a}n, Jos{\'e} del R and Schr{\"o}der, Michael and Niels Birbaumer} } @article {3216, title = {BCI Meeting 2005{\textendash}workshop on signals and recording methods.}, journal = {IEEE transactions on neural systems and rehabilitation engineering : a publication of the IEEE Engineering in Medicine and Biology Society}, volume = {14}, year = {2006}, month = {06/2006}, pages = {138{\textendash}141}, abstract = {This paper describes the highlights of presentations and discussions during the Third International BCI Meeting in a workshop that evaluated potential brain-computer interface (BCI) signals and currently available recording methods. It defined the main potential user populations and their needs, addressed the relative advantages and disadvantages of noninvasive and implanted (i.e., invasive) methodologies, considered ethical issues, and focused on the challenges involved in translating BCI systems from the laboratory to widespread clinical use. The workshop stressed the critical importance of developing useful applications that establish the practical value of BCI technology.}, keywords = {Brain-computer interface (BCI), electrophysiological signals, Rehabilitation}, issn = {1534-4320}, doi = {10.1109/TNSRE.2006.875583}, url = {http://www.ncbi.nlm.nih.gov/pubmed/16792279}, author = {Jonathan Wolpaw and Loeb, Gerald E. and Brendan Z. Allison and Emanuel Donchin and do Nascimento, Omar Feix and Heetderks, William J. and Nijboer, Femke and Shain, William G. and Turner, James N.} } @article {3133, title = {Brain-computer interface signal processing at the Wadsworth Center: mu and sensorimotor beta rhythms.}, journal = {Progress in brain research}, volume = {159}, year = {2006}, month = {02/2006}, pages = {411{\textendash}419}, abstract = {The Wadsworth brain-computer interface (BCI), based on mu and beta sensorimotor rhythms, uses one- and two-dimensional cursor movement tasks and relies on user training. This is a real-time closed-loop system. Signal processing consists of channel selection, spatial filtering, and spectral analysis. Feature translation uses a regression approach and normalization. Adaptation occurs at several points in this process on the basis of different criteria and methods. It can use either feedforward (e.g., estimating the signal mean for normalization) or feedback control (e.g., estimating feature weights for the prediction equation). We view this process as the interaction between a dynamic user and a dynamic system that coadapt over time. Understanding the dynamics of this interaction and optimizing its performance represent a major challenge for BCI research.}, keywords = {adaptation, BCI, Signal Processing}, issn = {0079-6123}, doi = {10.1016/S0079-6123(06)59026-0}, url = {http://www.ncbi.nlm.nih.gov/pubmed/17071245}, author = {Dennis J. McFarland and Krusienski, Dean J. and Jonathan Wolpaw} } @article {3192, title = {The cerebellum in maintenance of a motor skill: a hierarchy of brain and spinal cord plasticity underlies H-reflex conditioning.}, journal = {Learning \& memory (Cold Spring Harbor, N.Y.)}, volume = {13}, year = {2006}, month = {03/2006}, pages = {208{\textendash}215}, abstract = {Operant conditioning of the H-reflex, the electrical analog of the spinal stretch reflex, is a simple model of skill acquisition and involves plasticity in the spinal cord. Previous work showed that the cerebellum is essential for down-conditioning the H-reflex. This study asks whether the cerebellum is also essential for maintaining down-conditioning. After rats decreased the soleus H-reflex over 50 d in response to the down-conditioning protocol, the cerebellar output nuclei dentate and interpositus (DIN) were ablated, and down-conditioning continued for 50-100 more days. In naive (i.e., unconditioned) rats, DIN ablation itself has no significant long-term effect on H-reflex size. During down-conditioning prior to DIN ablation, eight Sprague-Dawley rats decreased the H-reflex to 57\% (+/-4 SEM) of control. It rose after ablation, stabilizing within 2 d at about 75\% and remaining there until approximately 40 d after ablation. It then rose to approximately 130\%, where it remained through the end of study 100 d after ablation. Thus, DIN ablation in down-conditioned rats caused an immediate increase and a delayed increase in the H-reflex. The final result was an H-reflex significantly larger than that prior to down-conditioning. Combined with previous work, these remarkable results suggest that the spinal cord plasticity directly responsible for down-conditioning, which survives only 5-10 d on its own, is maintained by supraspinal plasticity that survives approximately 40 d after loss of cerebellar output. Thus, H-reflex conditioning seems to depend on a hierarchy of brain and spinal cord plasticity to which the cerebellum makes an essential contribution.}, keywords = {Spinal Cord}, issn = {1072-0502}, doi = {10.1101/lm.92706}, url = {http://www.ncbi.nlm.nih.gov/pubmed/16585796}, author = {Jonathan Wolpaw and Xiang Yang Chen} } @article {3212, title = {A comparison of classification techniques for the P300 Speller.}, journal = {Journal of neural engineering}, volume = {3}, year = {2006}, month = {12/2006}, pages = {299{\textendash}305}, abstract = {This study assesses the relative performance characteristics of five established classification techniques on data collected using the P300 Speller paradigm, originally described by Farwell and Donchin (1988 Electroenceph. Clin. Neurophysiol. 70 510). Four linear methods: Pearson{\textquoteright}s correlation method (PCM), Fisher{\textquoteright}s linear discriminant (FLD), stepwise linear discriminant analysis (SWLDA) and a linear support vector machine (LSVM); and one nonlinear method: Gaussian kernel support vector machine (GSVM), are compared for classifying offline data from eight users. The relative performance of the classifiers is evaluated, along with the practical concerns regarding the implementation of the respective methods. The results indicate that while all methods attained acceptable performance levels, SWLDA and FLD provide the best overall performance and implementation characteristics for practical classification of P300 Speller data.}, keywords = {Normal Distribution}, issn = {1741-2560}, doi = {10.1088/1741-2560/3/4/007}, url = {http://www.ncbi.nlm.nih.gov/pubmed/17124334}, author = {Krusienski, Dean J. and Sellers, Eric W. and Cabestaing, Fran{\c c}ois and Bayoudh, Sabri and Dennis J. McFarland and Theresa M Vaughan and Jonathan Wolpaw} } @article {3190, title = {Corticospinal tract transection permanently abolishes H-reflex down-conditioning in rats.}, journal = {Journal of neurotrauma}, volume = {23}, year = {2006}, month = {11/2006}, pages = {1705{\textendash}1712}, abstract = {Previous studies have shown that corticospinal tract (CST) transection, but not transection of other major spinal cord tracts, prevents down-conditioning of the H-reflex, the electrical analog of the spinal stretch reflex. This study set out to determine whether the loss of the capacity for H-reflex down-conditioning caused by CST transection is permanent. Female Sprague-Dawley rats received CST, lateral column (LC), or dorsal column ascending tract (DA) transection at T8-9; 9-10 months later, they were exposed to the H-reflex down-conditioning protocol for 50 days. In the LC and DA rats, H-reflex size fell to 60 (+/- 9 SEM)\% and 60 (+/- 19)\%, respectively, of its initial size. This down-conditioning was comparable to that of normal rats. In contrast, H-reflex size in the CST rats rose to 170 (+/- 42)\% of its initial size. A similar rise does not occur in rats exposed to down-conditioning shortly after CST transection. These results indicate that CST transection permanently eliminates the capacity for H-reflex down-conditioning and has gradual long-term effects on sensorimotor cortex function. They imply that H-reflex down-conditioning can be a reliable measure of CST function for long-term studies of the effects of spinal cord injury and/or for evaluations of the efficacy of experimental therapeutic procedures, such as those intended to promote CST regeneration. The results also suggest that the role of sensorimotor cortex in down-conditioning extends beyond generation of the essential CST activity.}, keywords = {corticospinal tract, H-reflex conditioning, plasticity, rat, spinal cord injury}, issn = {0897-7151}, doi = {10.1089/neu.2006.23.1705}, url = {http://www.ncbi.nlm.nih.gov/pubmed/17115915}, author = {Xiang Yang Chen and Yi Chen and Lu Chen and Tennissen, Ann M. and Jonathan Wolpaw} } @article {3155, title = {Diurnal H-reflex variation in mice.}, journal = {Experimental brain research. Experimentelle Hirnforschung. Exp{\'e}rimentation c{\'e}r{\'e}brale}, volume = {168}, year = {2006}, month = {01/2006}, pages = {517{\textendash}528}, abstract = {Mice exhibit diurnal variation in complex motor behaviors, but little is known about diurnal variation in simple spinally mediated functions. This study describes diurnal variation in the H-reflex (HR), a wholly spinal and largely monosynaptic reflex. Six mice were implanted with tibial nerve cuff electrodes and electrodes in the soleus and gastrocnemius muscles, for recording of ongoing and nerve-evoked electromyographic activity (EMG). Stimulation and recording were under computer control 24 h/day. During a 10-day recording period, HR amplitude varied throughout the day, usually being larger in the dark than in the light. This diurnal HR variation could not be attributed solely to differences in the net ongoing level of descending and segmental excitation to the spinal cord or stimulus intensity. HRs were larger in the dark than in the light even after restricting the evoked responses to subsets of trials having similar ongoing EMG and M-responses. The diurnal variation in the HR was out of phase with that reported previously for rats, but was in phase with that observed in monkeys. These data, supported by those in other species, suggest that the supraspinal control of the excitability of the HR pathway varies throughout the day in a species-specific pattern. This variation should be taken into account in experimental and clinical studies of spinal reflexes recorded at different times of day.}, keywords = {circadian rhythm, Electromyography, implanted electrodes, Monosynaptic, Reflex, Spinal Cord}, issn = {0014-4819}, doi = {10.1007/s00221-005-0106-y}, url = {http://www.ncbi.nlm.nih.gov/pubmed/16151781}, author = {Jonathan S. Carp and Tennissen, Ann M. and Xiang Yang Chen and Jonathan Wolpaw} } @article {3211, title = {The education and re-education of the spinal cord.}, journal = {Progress in brain research}, volume = {157}, year = {2006}, month = {02/2006}, pages = {261{\textendash}280}, abstract = {In normal life, activity-dependent plasticity occurs in the spinal cord as well as in the brain. Like CNS plasticity elsewhere, this spinal cord plasticity can occur at many neuronal and synaptic sites and by a variety of mechanisms. Spinal cord plasticity is prominent in postnatal development and contributes to acquisition of standard behaviors such as locomotion and rapid withdrawal from pain. Later on in life, spinal cord plasticity contributes to acquisition and maintenance of specialized motor skills, and to compensation for the peripheral and central changes associated with aging, disease, and trauma. Mastery of even the simplest behaviors is accompanied by complex spinal and supraspinal plasticity. This complexity is necessary, to preserve the full roster of behaviors, and is also inevitable, due to the ubiquity of activity-dependent plasticity in the CNS. Careful investigation of spinal cord plasticity is essential for understanding motor skills; and, because of the relative simplicity and accessibility of the spinal cord, is a logical and convenient starting point for exploring skill acquisition. Appropriate induction and guidance of activity-dependent plasticity in the spinal cord is likely to be a key part of the realization of effective new rehabilitation methods for spinal cord injuries, cerebral palsy, and other chronic motor disorders.}, keywords = {behavior, conditioning, Learning, Memory, plasticity, Spinal Cord, spinal cord injury}, issn = {0079-6123}, doi = {10.1016/S0079-6123(06)57017-7}, url = {http://www.ncbi.nlm.nih.gov/pubmed/17167916}, author = {Jonathan Wolpaw} } @article {3202, title = {An evaluation of autoregressive spectral estimation model order for brain-computer interface applications.}, journal = {Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference}, volume = {1}, year = {2006}, month = {09/2006}, pages = {1323{\textendash}1326}, abstract = {Autoregressive (AR) spectral estimation is a popular method for modeling the electroencephalogram (EEG), and therefore the frequency domain EEG phenomena that are used for control of a brain-computer interface (BCI). Several studies have been conducted to evaluate the optimal AR model order for EEG, but the criteria used in these studies does not necessarily equate to the optimal AR model order for sensorimotor rhythm (SMR)-based BCI control applications. The present study confirms this by evaluating the EEG spectra of data obtained during control of SMR-BCI using different AR model orders and model evaluation criteria. The results indicate that the AR model order that optimizes SMR-BCI control performance is generally higher than the model orders that are frequently used in SMR-BCI studies.}, keywords = {User-Computer Interface}, issn = {1557-170X}, doi = {10.1109/IEMBS.2006.259822}, url = {http://www.ncbi.nlm.nih.gov/pubmed/17946038}, author = {Krusienski, D. J. and Dennis J. McFarland and Jonathan Wolpaw} } @article {3152, title = {H-reflex operant conditioning in mice.}, journal = {Journal of neurophysiology}, volume = {96}, year = {2006}, month = {10/2006}, pages = {1718{\textendash}1727}, abstract = {Rats, monkeys, and humans can alter the size of their spinal stretch reflex and its electrically induced analog, the H-reflex (HR), when exposed to an operant conditioning paradigm. Because this conditioning induces plasticity in the spinal cord, it offers a unique opportunity to identify the neuronal sites and mechanisms that underlie a well-defined change in a simple behavior. To facilitate these studies, we developed an HR operant conditioning protocol in mice, which are better suited to genetic manipulation and electrophysiological spinal cord study in vitro than rats or primates. Eleven mice under deep surgical anesthesia were implanted with tibial nerve stimulating electrodes and soleus and gastrocnemius intramuscular electrodes for recording ongoing and stimulus-evoked EMG activity. During the 24-h/day computer-controlled experiment, mice received a liquid reward for either increasing (up-conditioning) or decreasing (down-conditioning) HR amplitude while maintaining target levels of ongoing EMG and directly evoked EMG (M-responses). After 3-7 wk of conditioning, the HR amplitude was 133 +/- 7\% (SE) of control for up-conditioning and 71 +/- 8\% of control for down-conditioning. HR conditioning was successful (i.e., > or =20\% change in HR amplitude in the appropriate direction) in five of six up-conditioned animals (mean final HR amplitude = 139 +/- 5\% of control HR for successful mice) and in four of five down-conditioned animals (mean final HR amplitude = 63 +/- 8\% of control HR for successful mice). These effects were not attributable to differences in the net level of motoneuron pool excitation, stimulation strength, or distribution of HR trials throughout the day. Thus mice exhibit HR operant conditioning comparable with that observed in rats and monkeys.}, keywords = {Spinal Cord}, issn = {0022-3077}, doi = {10.1152/jn.00470.2006}, url = {http://www.ncbi.nlm.nih.gov/pubmed/16837659}, author = {Jonathan S. Carp and Tennissen, Ann M. and Xiang Yang Chen and Jonathan Wolpaw} } @article {3201, title = {Modulation in spinal circuits and corticospinal connections following nerve stimulation and operant conditioning.}, journal = {Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference}, volume = {1}, year = {2006}, month = {09/2006}, pages = {2138{\textendash}2141}, abstract = {Neural plasticity occurs throughout adult life. In healthy individuals, different spinal pathways are differently modulated during different daily activities. Drastic changes to nervous system activity and connections caused by injuries or diseases alter spinal reflexes, and this is often related to disturbed motor functions. In both health and disease, spinal reflexes are subject to substantial modifications. Plasticity in supraspinal descending connections is even more remarkable; corticospinal connectivity has been shown to be extremely plastic. In this session, we describe two approaches for possibly improving recovery after central nervous system (CNS) lesions. They are very different, but both involve repetitive nerve stimulation and CNS plasticity. The first approach is functional electrical stimulation (FES) of the common peroneal nerve, which has been used to treat foot drop in patients with CNS lesions. The second approach is operant conditioning of a spinal reflex. Spinal reflex operant conditioning studies in animal models have shown plastic changes in spinal cord neurons associated with this form of learning and improved locomotor function in incomplete spinal cord injured rats. Thus, reflex conditioning might be a robust approach to inducing plasticity at spinal and supraspinal levels. As a first step in establishing this approach and characterizing its effects in the human adult CNS, we are currently investigating the extent and time course of operant conditioning of the soleus H-reflex in healthy subjects. In results to date, all subjects (n=5) have changed reflex size in the correct direction to various degree (16-36\%) over 2-3 months of conditioning, indicating possibility that H-reflex conditioning can occur in humans. At the same time, the substantial inter-subject variation in the time course and extent of conditioning suggest that additional data are needed to establish its principal features. We hope that studying modulation and modification o- f the CNS by different approaches will help us further understand the plasticity of the human adult nervous system.}, keywords = {Spinal Cord}, issn = {1557-170X}, doi = {10.1109/IEMBS.2006.259544}, url = {http://www.ncbi.nlm.nih.gov/pubmed/17946939}, author = {Thompson, Aiko K. and Stein, Richard B. and Xiang Yang Chen and Jonathan Wolpaw} } @article {3193, title = {Motor learning changes GABAergic terminals on spinal motoneurons in normal rats.}, journal = {The European journal of neuroscience}, volume = {23}, year = {2006}, month = {01/2006}, pages = {141{\textendash}150}, abstract = {The role of spinal cord plasticity in motor learning is largely unknown. This study explored the effects of H-reflex operant conditioning, a simple model of motor learning, on GABAergic input to spinal motoneurons in rats. Soleus motoneurons were labeled by retrograde transport of a fluorescent tracer and GABAergic terminals on them were identified by glutamic acid decarboxylase (GAD)67 immunoreactivity. Three groups were studied: (i) rats in which down-conditioning had reduced the H-reflex (successful HRdown rats); (ii) rats in which down-conditioning had not reduced the H-reflex (unsuccessful HRdown rats) and (iii) unconditioned (naive) rats. The number, size and GAD density of GABAergic terminals, and their coverage of the motoneuron, were significantly greater in successful HRdown rats than in unsuccessful HRdown or naive rats. It is likely that these differences are due to modifications in terminals from spinal interneurons in lamina VI-VII and that the increased terminal number, size, GAD density and coverage in successful HRdown rats reflect and convey a corticospinal tract influence that changes motoneuron firing threshold and thereby decreases the H-reflex. GABAergic terminals in spinal cord change after spinal cord transection. The present results demonstrate that such spinal cord plasticity also occurs in intact rats in the course of motor learning and suggest that this plasticity contributes to skill acquisition.}, keywords = {activity-dependent plasticity, GABA, H-Reflex, Memory, Motor control, Spinal Cord}, issn = {0953-816X}, doi = {10.1111/j.1460-9568.2005.04547.x}, url = {http://www.ncbi.nlm.nih.gov/pubmed/16420424}, author = {Wang, Yu and Pillai, Shreejith and Jonathan Wolpaw and Xiang Yang Chen} } @article {3066, title = {Operant conditioning of H-reflex can correct a locomotor abnormality after spinal cord injury in rats.}, journal = {The Journal of neuroscience : the official journal of the Society for Neuroscience}, volume = {26}, year = {2006}, month = {11/2006}, pages = {12537{\textendash}12543}, abstract = {

This study asked whether operant conditioning of the H-reflex can modify locomotion in spinal cord-injured rats. Midthoracic transection of the right lateral column of the spinal cord produced a persistent asymmetry in the muscle activity underlying treadmill locomotion. The rats were then either exposed or not exposed to an H-reflex up-conditioning protocol that greatly increased right soleus motoneuron response to primary afferent input, and locomotion was reevaluated. H-reflex up-conditioning increased the right soleus burst and corrected the locomotor asymmetry. In contrast, the locomotor asymmetry persisted in the control rats. These results suggest that appropriately selected reflex conditioning protocols might improve function in people with partial spinal cord injuries. Such protocols might be especially useful when significant regeneration becomes possible and precise methods for reeducating the regenerated spinal cord neurons and synapses are needed for restoring effective function.

}, keywords = {H-reflex conditioning, Learning, Locomotion, Memory, Motor control, Rehabilitation, spinal cord injury, spinal cord plasticity}, issn = {1529-2401}, doi = {10.1523/JNEUROSCI.2198-06.2006}, url = {http://www.ncbi.nlm.nih.gov/pubmed/17135415}, author = {Yi Chen and Xiang Yang Chen and Jakeman, Lyn B. and Lu Chen and Stokes, Bradford T. and Jonathan Wolpaw} } @article {3191, title = {Operant conditioning of reciprocal inhibition in rat soleus muscle.}, journal = {Journal of neurophysiology}, volume = {96}, year = {2006}, month = {10/2006}, pages = {2144{\textendash}2150}, abstract = {Operant conditioning of the H-reflex, the electrical analog of the spinal stretch reflex (SSR), induces activity-dependent plasticity in the spinal cord and might be used to improve locomotion after spinal cord injury. To further assess the potential clinical significance of spinal reflex conditioning, this study asks whether another well-defined spinal reflex pathway, the disynaptic pathway underlying reciprocal inhibition (RI), can also be operantly conditioned. Sprague-Dawley rats were implanted with electromyographic (EMG) electrodes in right soleus (SOL) and tibialis anterior (TA) muscles and a stimulating cuff on the common peroneal (CP) nerve. When background EMG in both muscles remained in defined ranges, CP stimulation elicited the TA H-reflex and SOL RI. After collection of control data for 20 days, each rat was exposed for 50 days to up-conditioning (RIup mode) or down-conditioning (RIdown mode) in which food reward occurred if SOL RI evoked by CP stimulation was more (RIup mode) or less (RIdown mode) than a criterion. TA and SOL background EMG and TA M response remained stable. In every rat, RI conditioning was successful (i.e., change > or =20\% in the correct direction). In the RIup rats, final SOL RI averaged 171+/- 28\% (mean +/- SE) of control, and final TA H-reflex averaged 114 +/- 14\%. In the RIdown rats, final SOL RI averaged 37 +/- 13\% of control, and final TA H-reflex averaged 60 +/- 18\%. Final SOL RI and TA H-reflex sizes were significantly correlated. Thus like the SSR and the H-reflex, RI can be operantly conditioned; and conditioning one reflex can affect another reflex as well.}, keywords = {Reflex, Stretch}, issn = {0022-3077}, doi = {10.1152/jn.00253.2006}, url = {http://www.ncbi.nlm.nih.gov/pubmed/16807351}, author = {Xiang Yang Chen and Lu Chen and Yi Chen and Jonathan Wolpaw} } @article {3134, title = {A P300 event-related potential brain-computer interface (BCI): the effects of matrix size and inter stimulus interval on performance.}, journal = {Biological psychology}, volume = {73}, year = {2006}, month = {10/2006}, pages = {242{\textendash}252}, abstract = {We describe a study designed to assess properties of a P300 brain-computer interface (BCI). The BCI presents the user with a matrix containing letters and numbers. The user attends to a character to be communicated and the rows and columns of the matrix briefly intensify. Each time the attended character is intensified it serves as a rare event in an oddball sequence and it elicits a P300 response. The BCI works by detecting which character elicited a P300 response. We manipulated the size of the character matrix (either 3 x 3 or 6 x 6) and the duration of the inter stimulus interval (ISI) between intensifications (either 175 or 350 ms). Online accuracy was highest for the 3 x 3 matrix 175-ms ISI condition, while bit rate was highest for the 6 x 6 matrix 175-ms ISI condition. Average accuracy in the best condition for each subject was 88\%. P300 amplitude was significantly greater for the attended stimulus and for the 6 x 6 matrix. This work demonstrates that matrix size and ISI are important variables to consider when optimizing a BCI system for individual users and that a P300-BCI can be used for effective communication.}, keywords = {Amyotrophic Lateral Sclerosis, brain-computer interface, electroencephalogram, event-related potentials, P300, Rehabilitation}, issn = {0301-0511}, doi = {10.1016/j.biopsycho.2006.04.007}, url = {http://www.ncbi.nlm.nih.gov/pubmed/16860920}, author = {Sellers, Eric W. and Krusienski, Dean J. and Dennis J. McFarland and Theresa M Vaughan and Jonathan Wolpaw} } @article {3213, title = {Plastic changes in the human H-reflex pathway at rest following skillful cycling training.}, journal = {Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology}, volume = {117}, year = {2006}, month = {08/2006}, pages = {1682{\textendash}1691}, abstract = {OBJECTIVE: The spinal cord is capable of activity-dependent plasticity, but the extent of its participation in human motor learning is not known. Here, we tested the hypothesis that acquisition of a locomotor-related skill modulates the pathway of the H-reflex, a measure of spinal cord excitability that is susceptible to plastic changes. METHODS: Subjects were tested on their ability to establish a constant cycling speed on a recumbent bike despite frequent changes in pedal resistance. The coefficient of variation of speed (CV(speed)) measured their ability to acquire this skill (decreasing CV(speed) with training reflects performance improvements). Soleus H-reflexes were taken at rest before and after cycling. RESULTS: Ability to establish a target speed increased and H-reflex size decreased more after cycling training involving frequent changes in pedal resistance that required calibrated locomotor compensatory action than with training involving constant pedal resistances and lesser compensation. The degree of performance improvement correlated with the reduction in the amplitude of the H-reflex. CONCLUSIONS: Skillful establishment of a constant cycling speed despite changing pedal resistances is associated with persistent modulation of activity in spinal pathways. SIGNIFICANCE: Recalibration of activity in the H-reflex pathway may be part of the control strategy required for locomotor-related skill acquisition.}, keywords = {H-Reflex, Locomotion, Memory, plasticity, Spinal Cord}, issn = {1388-2457}, doi = {10.1016/j.clinph.2006.04.019}, url = {http://www.ncbi.nlm.nih.gov/pubmed/16793333}, author = {Mazzocchio, Riccardo and Kitago, Tomoko and Liuzzi, Gianpiero and Jonathan Wolpaw and Cohen, Leonardo G.} } @article {3153, title = {Plasticity from muscle to brain.}, journal = {Progress in neurobiology}, volume = {78}, year = {2006}, month = {02/2006}, pages = {233{\textendash}263}, abstract = {Recognition that the entire central nervous system (CNS) is highly plastic, and that it changes continually throughout life, is a relatively new development. Until very recently, neuroscience has been dominated by the belief that the nervous system is hardwired and changes at only a few selected sites and by only a few mechanisms. Thus, it is particularly remarkable that Sir John Eccles, almost from the start of his long career nearly 80 years ago, focused repeatedly and productively on plasticity of many different kinds and in many different locations. He began with muscles, exploring their developmental plasticity and the functional effects of the level of motor unit activity and of cross-reinnervation. He moved into the spinal cord to study the effects of axotomy on motoneuron properties and the immediate and persistent functional effects of repetitive afferent stimulation. In work that combined these two areas, Eccles explored the influences of motoneurons and their muscle fibers on one another. He studied extensively simple spinal reflexes, especially stretch reflexes, exploring plasticity in these reflex pathways during development and in response to experimental manipulations of activity and innervation. In subsequent decades, Eccles focused on plasticity at central synapses in hippocampus, cerebellum, and neocortex. His endeavors extended from the plasticity associated with CNS lesions to the mechanisms responsible for the most complex and as yet mysterious products of neuronal plasticity, the substrates underlying learning and memory. At multiple levels, Eccles{\textquoteright} work anticipated and helped shape present-day hypotheses and experiments. He provided novel observations that introduced new problems, and he produced insights that continue to be the foundation of ongoing basic and clinical research. This article reviews Eccles{\textquoteright} experimental and theoretical contributions and their relationships to current endeavors and concepts. It emphasizes aspects of his contributions that are less well known at present and yet are directly relevant to contemporary issues.}, keywords = {activity-dependent, John Eccles, Learning, Memory, motor unit, muscle, plasticity, Spinal Cord}, issn = {0301-0082}, doi = {10.1016/j.pneurobio.2006.03.001}, url = {http://www.ncbi.nlm.nih.gov/pubmed/16647181}, author = {Jonathan Wolpaw and Jonathan S. Carp} } @article {3154, title = {Sensorimotor cortex ablation prevents H-reflex up-conditioning and causes a paradoxical response to down-conditioning in rats.}, journal = {Journal of neurophysiology}, volume = {96}, year = {2006}, month = {07/2006}, pages = {119{\textendash}127}, abstract = {Operant conditioning of the H-reflex, a simple model for skill acquisition, requires the corticospinal tract (CST) and does not require other major descending pathways. To further explore its mechanisms, we assessed the effects of ablating contralateral sensorimotor cortex (cSMC). In 22 Sprague-Dawley rats, the hindlimb area of left cSMC was ablated. EMG electrodes were implanted in the right soleus muscle and a stimulating cuff was placed around the right posterior tibial nerve. When EMG remained in a specified range, nerve stimulation just above the M response threshold elicited the H-reflex. In control mode, no reward occurred. In conditioning mode, reward occurred if H-reflex size was above (HRup mode) or below (HRdown mode) a criterion value. After exposure to the control mode for > or = 10 days, each rat was exposed for another 50 days to the control mode, the HRup mode, or the HRdown mode. In control and HRup rats, final H-reflex size was not significantly different from initial H-reflex size. In contrast, in HRdown rats, final H-reflex size was significantly increased to an average of 136\% of initial size. Thus like recent CST transection, cSMC ablation greatly impaired up-conditioning. However, unlike recent CST transection, cSMC produced a paradoxical response to down-conditioning: the H-reflex actually increased. These results confirm the critical role of cSMC in H-reflex conditioning and suggest that this role extends beyond producing essential CST activity. Its interactions with ipsilateral SMC or other areas contribute to the complex pattern of spinal and supraspinal plasticity that underlies H-reflex conditioning.}, keywords = {Somatosensory Cortex}, issn = {0022-3077}, doi = {10.1152/jn.01271.2005}, url = {http://www.ncbi.nlm.nih.gov/pubmed/16598062}, author = {Xiang Yang Chen and Jonathan S. Carp and Lu Chen and Jonathan Wolpaw} } @article {3217, title = {The Third International Meeting on Brain-Computer Interface Technology: making a difference.}, journal = {IEEE transactions on neural systems and rehabilitation engineering : a publication of the IEEE Engineering in Medicine and Biology Society}, volume = {14}, year = {2006}, month = {06/2006}, pages = {126{\textendash}127}, abstract = {This special issue of the IEEE TRANSACTIONS ON NEURAL SYSTEMS AND REHABILITATION ENGINEERING provides a representative and comprehensive bird{\textquoteright}s-eye view of the most recent developments in brain-computer interface (BCI) technology from laboratories around the world. The 30 research communications and papers are the direct outcome of the Third International Meeting on Brain-Computer Interface Technology held at the Rensselaerville Institute, Rensselaerville, NY, in June 2005. Fifty-three research groups from North and South America, Europe, and Asia, representing the majority of all the existing BCI laboratories around the world, participated in this highly focused meeting sponsored by the National Institutes of Health and organized by the BCI Laboratory of the Wadsworth Center of the New York State Department of Health. As demonstrated by the papers in this special issue, the rapid advances in BCI research and development make this technology capable of providing communication and control to people severely disabled by amyotrophic lateral sclerosis (ALS), brainstem stroke, cerebral palsy, and other neuromuscular disorders. Future work is expected to improve the performance and utility of BCIs, and to focus increasingly on making them a viable, practical, and affordable communication alternative for many thousands of severely disabled people worldwide.}, keywords = {User-Computer Interface}, issn = {1534-4320}, doi = {10.1109/TNSRE.2006.875649}, url = {http://www.ncbi.nlm.nih.gov/pubmed/16792275}, author = {Theresa M Vaughan and Jonathan Wolpaw} } @article {3218, title = {Treadmill training after spinal cord injury: good but not better.}, journal = {Neurology}, volume = {66}, year = {2006}, month = {02/2006}, pages = {466{\textendash}467}, keywords = {Walking}, issn = {1526-632X}, doi = {10.1212/01.wnl.0000203915.14930.b4}, url = {http://www.ncbi.nlm.nih.gov/pubmed/16505294}, author = {Jonathan Wolpaw} } @article {2177, title = {The Wadsworth BCI Research and Development Program: At Home with BCI.}, journal = {IEEE Trans Neural Syst Rehabil Eng}, volume = {14}, year = {2006}, month = {06/2006}, pages = {229-33}, abstract = {

The ultimate goal of brain-computer interface (BCI) technology is to provide communication and control capacities to people with severe motor disabilities. BCI research at the Wadsworth Center focuses primarily on noninvasive,\ electroencephalography\ (EEG)-based BCI methods. We have shown that people, including those with severe motor disabilities, can learn to use sensorimotor rhythms (SMRs) to move a cursor rapidly and accurately in one or two dimensions. We have also improved P300-based BCI operation. We are now translating this laboratory-proven BCI technology into a system that can be used by severely disabled people in their homes with minimal ongoing technical oversight. To accomplish this, we have: improved our general-purpose BCI software (BCI2000); improved online adaptation and feature translation for SMR-based BCI operation; improved the accuracy and bandwidth of P300-based BCI operation; reduced the\ complexity\ of system hardware and software and begun to evaluate home system use in appropriate users. These developments have resulted in prototype systems for every day use in people{\textquoteright}s homes.

}, keywords = {Animals, Brain, Electroencephalography, Evoked Potentials, Humans, Neuromuscular Diseases, New York, Research, Switzerland, Therapy, Computer-Assisted, Universities, User-Computer Interface}, issn = {1534-4320}, doi = {10.1109/TNSRE.2006.875577}, url = {http://www.ncbi.nlm.nih.gov/pubmed/16792301}, author = {Theresa M Vaughan and Dennis J. McFarland and Gerwin Schalk and Sarnacki, William A and Krusienski, Dean J and Sellers, Eric W and Jonathan Wolpaw} } @article {3195, title = {Ablation of cerebellar nuclei prevents H-reflex down-conditioning in rats.}, journal = {Learning \& memory (Cold Spring Harbor, N.Y.)}, volume = {12}, year = {2005}, month = {05/2005}, pages = {248{\textendash}254}, abstract = {While studies of cerebellar involvement in learning and memory have described plasticity within the cerebellum, its role in acquisition of plasticity elsewhere in the CNS is largely unexplored. This study set out to determine whether the cerebellum is needed for acquisition of the spinal cord plasticity that underlies operantly conditioned decrease in the H-reflex, the electrical analog of the spinal stretch reflex. Rats in which the cerebellar output nuclei dentate and interpositus (DIN) had been ablated were exposed for 50 d to the H-reflex down-conditioning protocol. DIN ablation, which in itself had no significant long-term effect on H-reflex size, entirely prevented acquisition of a smaller H-reflex. Since previous studies show that corticospinal tract (CST) transection also prevents down-conditioning while transection of the rubrospinal tract and other major descending tracts does not, this result implies that DIN output that affects cortex is essential for generation of the CST activity that induces the spinal cord plasticity, which is, in turn, directly responsible for the smaller H-reflex. The result extends the role of the cerebellum in learning and memory to include participation in induction of plasticity elsewhere in the CNS, specifically in the spinal cord. The cerebellum might simply support processes in sensorimotor cortex or elsewhere that change the spinal cord, or the cerebellum itself might undergo plasticity similar to that occurring with vestibulo-ocular reflex (VOR) or eyeblink conditioning.}, keywords = {Reflex, Vestibulo-Ocular}, issn = {1072-0502}, doi = {10.1101/lm.91305}, url = {http://www.ncbi.nlm.nih.gov/pubmed/15930503}, author = {Xiang Yang Chen and Jonathan Wolpaw} } @article {3138, title = {Brain-computer interface (BCI) operation: signal and noise during early training sessions.}, journal = {Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology}, volume = {116}, year = {2005}, month = {01/2005}, pages = {56{\textendash}62}, abstract = {OBJECTIVE: People can learn to control mu (8-12 Hz) or beta (18-25 Hz) rhythm amplitude in the electroencephalogram (EEG) recorded over sensorimotor cortex and use it to move a cursor to a target on a video screen. The recorded signal may also contain electromyogram (EMG) and other non-EEG artifacts. This study examines the presence and characteristics of EMG contamination during new users{\textquoteright} initial brain-computer interface (BCI) training sessions, as they first attempt to acquire control over mu or beta rhythm amplitude and to use that control to move a cursor to a target. METHODS: In the standard one-dimensional format, a target appears along the right edge of the screen and 1s later the cursor appears in the middle of the left edge and moves across the screen at a fixed rate with its vertical movement controlled by a linear function of mu or beta rhythm amplitude. In the basic two-choice version, the target occupies the upper or lower half of the right edge. The user{\textquoteright}s task is to move the cursor vertically so that it hits the target when it reaches the right edge. The present data comprise the first 10 sessions of BCI training from each of 7 users. Their data were selected to illustrate the variations seen in EMG contamination across users. RESULTS: Five of the 7 users learned to change rhythm amplitude appropriately, so that the cursor hit the target. Three of these 5 showed no evidence of EMG contamination. In the other two of these 5, EMG was prominent in early sessions, and tended to be associated with errors rather than with hits. As EEG control improved over the 10 sessions, this EMG contamination disappeared. In the remaining two users, who never acquired actual EEG control, EMG was prominent in initial sessions and tended to move the cursor to the target. This EMG contamination was still detectable by Session 10. CONCLUSIONS: EMG contamination arising from cranial muscles is often present early in BCI training and gradually wanes. In those users who eventually acquire EEG control, early target-related EMG contamination may be most prominent for unsuccessful trials, and may reflect user frustration. In those users who never acquire EEG control, EMG may initially serve to move the cursor toward the target. Careful and comprehensive topographical and spectral analyses throughout user training are essential for detecting EMG contamination and differentiating between cursor control provided by EEG control and cursor control provided by EMG contamination. SIGNIFICANCE: Artifacts such as EMG are common in EEG recordings. Comprehensive spectral and topographical analyses are necessary to detect them and ensure that they do not masquerade as, or interfere with acquisition of, actual EEG-based cursor control.}, keywords = {brain-computer interface, EEG, Electroencephalography, Learning, mu rhythm, sensorimotor cortex}, issn = {1388-2457}, doi = {10.1016/j.clinph.2004.07.004}, url = {http://www.ncbi.nlm.nih.gov/pubmed/15589184}, author = {Dennis J. McFarland and Sarnacki, William A. and Theresa M Vaughan and Jonathan Wolpaw} } @article {3194, title = {The interaction of a new motor skill and an old one: H-reflex conditioning and locomotion in rats.}, journal = {The Journal of neuroscience : the official journal of the Society for Neuroscience}, volume = {25}, year = {2005}, month = {07/2005}, pages = {6898{\textendash}6906}, abstract = {New and old motor skills can interfere with each other or interact in other ways. Because each skill entails a distributed pattern of activity-dependent plasticity, investigation of their interactions is facilitated by simple models. In a well characterized model of simple learning, rats and monkeys gradually change the size of the H-reflex, the electrical analog of the spinal stretch reflex. This study evaluates in normal rats the interactions of this new skill of H-reflex conditioning with the old well established skill of overground locomotion. In rats in which the soleus H-reflex elicited in the conditioning protocol (i.e., the conditioning H-reflex) had been decreased by down-conditioning, the H-reflexes elicited during the stance and swing phases of locomotion (i.e., the locomotor H-reflexes) were also smaller. Similarly, in rats in which the conditioning H-reflex had been increased by up-conditioning, the locomotor H-reflexes were also larger. Soleus H-reflex conditioning did not affect the duration, length, or right/left symmetry of the step cycle. However, the conditioned change in the stance H-reflex was positively correlated with change in the amplitude of the soleus locomotor burst, and the correlation was consistent with current estimates of the contribution of primary afferent input to the burst. Although H-reflex conditioning and locomotion did not interfere with each other, H-reflex conditioning did affect how locomotion was produced: it changed soleus burst amplitude and may have induced compensatory changes in the activity of other muscles. These results illustrate and clarify the subtlety and complexity of skill interactions. They also suggest that H-reflex conditioning might be used to improve the abnormal locomotion produced by spinal cord injury or other disorders of supraspinal control.}, keywords = {H-reflex conditioning, Learning, Locomotion, memory consolidation, Motor control, Rehabilitation, spinal cord plasticity}, issn = {1529-2401}, doi = {10.1523/JNEUROSCI.1684-05.2005}, url = {http://www.ncbi.nlm.nih.gov/pubmed/16033899}, author = {Yi Chen and Xiang Yang Chen and Jakeman, Lyn B. and Gerwin Schalk and Stokes, Bradford T. and Jonathan Wolpaw} } @article {3156, title = {Long-term spinal reflex studies in awake behaving mice.}, journal = {Journal of neuroscience methods}, volume = {149}, year = {2005}, month = {12/2005}, pages = {134{\textendash}143}, abstract = {The increasing availability of genetic variants of mice has facilitated studies of the roles of specific molecules in specific behaviors. The contributions of such studies could be strengthened and extended by correlation with detailed information on the patterns of motor commands throughout the course of specific behaviors in freely moving animals. Previously reported methodologies for long-term recording of electromyographic activity (EMG) in mice using implanted electrodes were designed for intermittent, but not continuous operation. This report describes the fabrication, implantation, and utilization of fine wire electrodes for continuous long-term recordings of spontaneous and nerve-evoked EMG in mice. Six mice were implanted with a tibial nerve cuff electrode and EMG electrodes in soleus and gastrocnemius muscles. Wires exited through a skin button and traveled through an armored cable to an electrical commutator. In mice implanted for 59-144 days, ongoing EMG was monitored continuously (i.e., 24 h/day, 7 days/week) by computer for 18-92 days (total intermittent recording for 25-130 days). When the ongoing EMG criteria were met, the computer applied the nerve stimulus, recorded the evoked EMG response, and determined the size of the M-response (MR) and the H-reflex (HR). It continually adjusted stimulation intensity to maintain a stable MR size. Stable recordings of ongoing EMG, MR, and HR were obtained typically 3 weeks after implantation. This study demonstrates the feasibility of long-term continuous EMG recordings in mice for addressing a variety of neurophysiological and behavioral issues.}, keywords = {Electromyography, implanted electrodes, Monosynaptic, Spinal Cord}, issn = {0165-0270}, doi = {10.1016/j.jneumeth.2005.05.012}, url = {http://www.ncbi.nlm.nih.gov/pubmed/16026848}, author = {Jonathan S. Carp and Tennissen, Ann M. and Xiang Yang Chen and Gerwin Schalk and Jonathan Wolpaw} } @article {3220, title = {Patients with ALS can use sensorimotor rhythms to operate a brain-computer interface.}, journal = {Neurology}, volume = {64}, year = {2005}, month = {05/2005}, pages = {1775{\textendash}1777}, abstract = {People with severe motor disabilities can maintain an acceptable quality of life if they can communicate. Brain-computer interfaces (BCIs), which do not depend on muscle control, can provide communication. Four people severely disabled by ALS learned to operate a BCI with EEG rhythms recorded over sensorimotor cortex. These results suggest that a sensorimotor rhythm-based BCI could help maintain quality of life for people with ALS.}, keywords = {User-Computer Interface}, issn = {1526-632X}, doi = {10.1212/01.WNL.0000158616.43002.6D}, url = {http://www.ncbi.nlm.nih.gov/pubmed/15911809}, author = {K{\"u}bler, A. and Nijboer, F. and Mellinger, J. and Theresa M Vaughan and Pawelzik, H. and Gerwin Schalk and Dennis J. McFarland and Niels Birbaumer and Jonathan Wolpaw} } @article {2169, title = {Patients with ALS can use sensorimotor rhythms to operate a brain-computer interface.}, journal = {Neurology}, volume = {64}, year = {2005}, month = {05/2005}, pages = {1775-7}, abstract = {

People with severe motor disabilities can maintain an acceptable quality of life if they can communicate.\ Brain-computer interfaces\ (BCIs), which do not depend on muscle control, can provide communication. Four people severely disabled by ALS learned to operate a BCI with EEG rhythms recorded over sensorimotor cortex. These results suggest that a sensorimotor rhythm-based\ BCI could help maintain quality of life for people with ALS.

}, keywords = {Aged, Amyotrophic Lateral Sclerosis, Electroencephalography, Evoked Potentials, Motor, Evoked Potentials, Somatosensory, Female, Humans, Imagination, Male, Middle Aged, Motor Cortex, Movement, Paralysis, Photic Stimulation, Prostheses and Implants, Somatosensory Cortex, Treatment Outcome, User-Computer Interface}, issn = {1526-632X}, doi = {10.1212/01.WNL.0000158616.43002.6D}, url = {http://www.ncbi.nlm.nih.gov/pubmed/15911809}, author = {K{\"u}bler, A. and Nijboer, F and Mellinger, J{\"u}rgen and Theresa M Vaughan and Pawelzik, H and Gerwin Schalk and Dennis J. McFarland and Niels Birbaumer and Jonathan Wolpaw} } @conference {3435, title = {Recording Options for Brain-Computer Interfaces.}, booktitle = {Proceedings to the 1st Conference on Augmented Cognition}, year = {2005}, month = {2005}, author = {Gerwin Schalk and Jonathan Wolpaw} } @proceedings {2694, title = {Recording Options for Brain-Computer Interfaces}, year = {2005}, month = {2005}, author = {Gerwin Schalk and Jonathan Wolpaw} } @article {3137, title = {Sensorimotor rhythm-based brain-computer interface (BCI): feature selection by regression improves performance.}, journal = {IEEE transactions on neural systems and rehabilitation engineering : a publication of the IEEE Engineering in Medicine and Biology Society}, volume = {13}, year = {2005}, month = {09/2005}, pages = {372{\textendash}379}, abstract = {People can learn to control electroencephalogram (EEG) features consisting of sensorimotor rhythm amplitudes and can use this control to move a cursor in one or two dimensions to a target on a screen. In the standard one-dimensional application, the cursor moves horizontally from left to right at a fixed rate while vertical cursor movement is continuously controlled by sensorimotor rhythm amplitude. The right edge of the screen is divided among 2-6 targets, and the user{\textquoteright}s goal is to control vertical cursor movement so that the cursor hits the correct target when it reaches the right edge. Up to the present, vertical cursor movement has been a linear function of amplitude in a specific frequency band [i.e., 8-12 Hz (mu) or 18-26 Hz (beta)] over left and/or right sensorimotor cortex. The present study evaluated the effect of controlling cursor movement with a weighted combination of these amplitudes in which the weights were determined by an regression algorithm on the basis of the user{\textquoteright}s past performance. Analyses of data obtained from a representative set of trained users indicated that weighted combinations of sensorimotor rhythm amplitudes could support cursor control significantly superior to that provided by a single feature. Inclusion of an interaction term further improved performance. Subsequent online testing of the regression algorithm confirmed the improved performance predicted by the offline analyses. The results demonstrate the substantial value for brain-computer interface applications of simple multivariate linear algorithms. In contrast to many classification algorithms, such linear algorithms can easily incorporate multiple signal features, can readily adapt to changes in the user{\textquoteright}s control of these features, and can accommodate additional targets without major modifications.}, issn = {1534-4320}, doi = {10.1109/TNSRE.2005.848627}, url = {http://www.ncbi.nlm.nih.gov/pubmed/16200760}, author = {Dennis J. McFarland and Jonathan Wolpaw} } @proceedings {2695, title = {Towards two-dimensional cursor control using electrocorticographic signals}, year = {2005}, author = {Gerwin Schalk and Leuthardt, E C and Moran, D and Miller, K.J. and Ojemann, J G and Jonathan Wolpaw} } @conference {3437, title = {Towards two-dimensional cursor control using electrocorticographic signals.}, booktitle = {Proceedings to the 11th International Conference on Human-Computer Interaction}, year = {2005}, month = {2005}, author = {Gerwin Schalk and Leuthardt, E C and Moran, D and Miller, K.J. and Ojemann, J G and Jonathan Wolpaw} } @proceedings {2693, title = {Tracking of the mu rhythm using an empirically derived matched filter}, year = {2005}, month = {03/2005}, author = {Krusienski, Dean J and Gerwin Schalk and Dennis J. McFarland and Jonathan Wolpaw} } @conference {3436, title = {Tracking of the mu rhythm using an empirically derived matched filter.}, booktitle = {Proc. IEEE International Conference of Neural Engineering}, year = {2005}, month = {03/2005}, publisher = {IEEE}, organization = {IEEE}, address = {Arlington, VA}, keywords = {bioelectric potentials, Brain Computer Interfaces, brain modeling, brain-computer interface, communication device, communication system control, cortical mu rhythm modulation, EEG, Electroencephalography, empirically derived matched filter, handicapped aids, laboratories, matched filters, medical signal detection, medical signal processing, monitoring, motor imagery, mu rhythm tracking, noninvasive treatment, rhythm, synchronous motors, two-dimensional cursor control data}, isbn = {0-7803-8710-4}, doi = {10.1109/CNE.2005.1419559}, url = {http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=1419559}, author = {Krusienski, Dean J and Gerwin Schalk and Dennis J. McFarland and Jonathan Wolpaw} } @article {2167, title = {The BCI Competition 2003: Progress and perspectives in detection and discrimination of EEG single trials.}, journal = {IEEE Trans Biomed Eng}, volume = {51}, year = {2004}, month = {06/2004}, pages = {1044-51}, abstract = {Interest in developing a new method of man-to-machine communication--a brain-computer interface (BCI)--has grown steadily over the past few decades. BCIs create a new communication channel between the brain and an output device by bypassing conventional motor output pathways of nerves and muscles. These systems use signals recorded from the scalp, the surface of the cortex, or from inside the brain to enable users to control a variety of applications including simple word-processing software and orthotics. BCI technology could therefore provide a new communication and control option for individuals who cannot otherwise express their wishes to the outside world. Signal processing and classification methods are essential tools in the development of improved BCI technology. We organized the BCI Competition 2003 to evaluate the current state of the art of these tools. Four laboratories well versed in EEG-based BCI research provided six data sets in a documented format. We made these data sets (i.e., labeled training sets and unlabeled test sets) and their descriptions available on the Internet. The goal in the competition was to maximize the performance measure for the test labels. Researchers worldwide tested their algorithms and competed for the best classification results. This paper describes the six data sets and the results and function of the most successful algorithms.}, keywords = {Adult, Algorithms, Amyotrophic Lateral Sclerosis, Artificial Intelligence, Brain, Cognition, Databases, Factual, Electroencephalography, Evoked Potentials, Humans, Reproducibility of Results, Sensitivity and Specificity, User-Computer Interface}, issn = {0018-9294}, doi = {10.1109/TBME.2004.826692}, author = {Benjamin Blankertz and M{\"u}ller, Klaus-Robert and Curio, Gabriel and Theresa M Vaughan and Gerwin Schalk and Jonathan Wolpaw and Schl{\"o}gl, Alois and Neuper, Christa and Pfurtscheller, Gert and Hinterberger, T. and Schr{\"o}der, Michael and Niels Birbaumer} } @article {3222, title = {The BCI Competition 2003: progress and perspectives in detection and discrimination of EEG single trials.}, journal = {IEEE transactions on bio-medical engineering}, volume = {51}, year = {2004}, month = {06/2004}, pages = {1044{\textendash}1051}, abstract = {Interest in developing a new method of man-to-machine communication{\textendash}a brain-computer interface (BCI){\textendash}has grown steadily over the past few decades. BCIs create a new communication channel between the brain and an output device by bypassing conventional motor output pathways of nerves and muscles. These systems use signals recorded from the scalp, the surface of the cortex, or from inside the brain to enable users to control a variety of applications including simple word-processing software and orthotics. BCI technology could therefore provide a new communication and control option for individuals who cannot otherwise express their wishes to the outside world. Signal processing and classification methods are essential tools in the development of improved BCI technology. We organized the BCI Competition 2003 to evaluate the current state of the art of these tools. Four laboratories well versed in EEG-based BCI research provided six data sets in a documented format. We made these data sets (i.e., labeled training sets and unlabeled test sets) and their descriptions available on the Internet. The goal in the competition was to maximize the performance measure for the test labels. Researchers worldwide tested their algorithms and competed for the best classification results. This paper describes the six data sets and the results and function of the most successful algorithms.}, keywords = {augmentative communication, BCI, beta-rhythm, brain-computer interface, EEG, ERP, imagined hand movements, lateralized readiness potential, mu-rhythm, P300, Rehabilitation, single-trial classification, slow cortical potentials}, issn = {0018-9294}, doi = {10.1109/TBME.2004.826692}, url = {http://www.ncbi.nlm.nih.gov/pubmed/15188876}, author = {Benjamin Blankertz and M{\"u}ller, Klaus-Robert and Curio, Gabriel and Theresa M Vaughan and Gerwin Schalk and Jonathan Wolpaw and Schl{\"o}gl, Alois and Neuper, Christa and Pfurtscheller, Gert and Hinterberger, Thilo and Schr{\"o}der, Michael and Niels Birbaumer} } @article {2166, title = {BCI2000: a general-purpose brain-computer interface (BCI) system.}, journal = {IEEE Trans Biomed Eng}, volume = {51}, year = {2004}, month = {06/2004}, pages = {1034-43}, abstract = {Many laboratories have begun to develop brain-computer interface (BCI) systems that provide communication and control capabilities to people with severe motor disabilities. Further progress and realization of practical applications depends on systematic evaluations and comparisons of different brain signals, recording methods, processing algorithms, output formats, and operating protocols. However, the typical BCI system is designed specifically for one particular BCI method and is, therefore, not suited to the systematic studies that are essential for continued progress. In response to this problem, we have developed a documented general-purpose BCI research and development platform called BCI2000. BCI2000 can incorporate alone or in combination any brain signals, signal processing methods, output devices, and operating protocols. This report is intended to describe to investigators, biomedical engineers, and computer scientists the concepts that the BC12000 system is based upon and gives examples of successful BCI implementations using this system. To date, we have used BCI2000 to create BCI systems for a variety of brain signals, processing methods, and applications. The data show that these systems function well in online operation and that BCI2000 satisfies the stringent real-time requirements of BCI systems. By substantially reducing labor and cost, BCI2000 facilitates the implementation of different BCI systems and other psychophysiological experiments. It is available with full documentation and free of charge for research or educational purposes and is currently being used in a variety of studies by many research groups.}, keywords = {Algorithms, Brain, Cognition, Communication Aids for Disabled, Computer Peripherals, Electroencephalography, Equipment Design, Equipment Failure Analysis, Evoked Potentials, Humans, Systems Integration, User-Computer Interface}, issn = {0018-9294}, doi = {10.1109/TBME.2004.827072}, author = {Gerwin Schalk and Dennis J. McFarland and Hinterberger, T. and Niels Birbaumer and Jonathan Wolpaw} } @article {3223, title = {BCI2000: a general-purpose brain-computer interface (BCI) system.}, journal = {IEEE transactions on bio-medical engineering}, volume = {51}, year = {2004}, month = {06/2004}, pages = {1034{\textendash}1043}, abstract = {Many laboratories have begun to develop brain-computer interface (BCI) systems that provide communication and control capabilities to people with severe motor disabilities. Further progress and realization of practical applications depends on systematic evaluations and comparisons of different brain signals, recording methods, processing algorithms, output formats, and operating protocols. However, the typical BCI system is designed specifically for one particular BCI method and is, therefore, not suited to the systematic studies that are essential for continued progress. In response to this problem, we have developed a documented general-purpose BCI research and development platform called BCI2000. BCI2000 can incorporate alone or in combination any brain signals, signal processing methods, output devices, and operating protocols. This report is intended to describe to investigators, biomedical engineers, and computer scientists the concepts that the BC12000 system is based upon and gives examples of successful BCI implementations using this system. To date, we have used BCI2000 to create BCI systems for a variety of brain signals, processing methods, and applications. The data show that these systems function well in online operation and that BCI2000 satisfies the stringent real-time requirements of BCI systems. By substantially reducing labor and cost, BCI2000 facilitates the implementation of different BCI systems and other psychophysiological experiments. It is available with full documentation and free of charge for research or educational purposes and is currently being used in a variety of studies by many research groups.}, keywords = {User-Computer Interface}, issn = {0018-9294}, doi = {10.1109/TBME.2004.827072}, url = {http://www.ncbi.nlm.nih.gov/pubmed/15188875}, author = {Gerwin Schalk and Dennis J. McFarland and Hinterberger, Thilo and Niels Birbaumer and Jonathan Wolpaw} } @article {2168, title = {A brain-computer interface using electrocorticographic signals in humans.}, journal = {J Neural Eng}, volume = {1}, year = {2004}, month = {06/2004}, pages = {63-71}, abstract = {

Brain-computer interfaces\ (BCIs) enable users to control devices with electroencephalographic (EEG) activity from the scalp or with single-neuron activity from within the\ brain. Both methods have disadvantages: EEG has limited resolution and requires extensive training, while single-neuron recording entails significant clinical risks and has limited stability. We demonstrate here for the first time that electrocorticographic (ECoG) activity recorded from the surface of the\ brain\ can enable users to control a one-dimensional\ computer\ cursor rapidly and accurately. We first identified ECoG signals that were associated with different types of motor and speech imagery. Over brief training periods of 3-24 min, four patients then used these signals to master closed-loop control and to achieve success rates of 74-100\% in a one-dimensional binary task. In additional open-loop experiments, we found that ECoG signals at frequencies up to 180 Hz encoded substantial information about the direction of two-dimensional joystick movements. Our results suggest that an ECoG-based BCI could provide for people with severe motor disabilities a non-muscular communication and control option that is more powerful than EEG-based BCIs and is potentially more stable and less traumatic than BCIs that use electrodes penetrating the\ brain.

}, keywords = {Adult, Brain, Communication Aids for Disabled, Computer Peripherals, Diagnosis, Computer-Assisted, Electrodes, Implanted, Electroencephalography, Evoked Potentials, Female, Humans, Imagination, Male, Movement Disorders, User-Computer Interface}, issn = {1741-2560}, doi = {10.1088/1741-2560/1/2/001}, url = {http://www.ncbi.nlm.nih.gov/pubmed/15876624}, author = {Leuthardt, E C and Gerwin Schalk and Jonathan Wolpaw and Ojemann, J G and Moran, D} } @article {3219, title = {Brain-computer interfaces (BCIs) for communication and control: a mini-review.}, journal = {Supplements to Clinical neurophysiology}, volume = {57}, year = {2004}, month = {02/2004}, pages = {607{\textendash}613}, keywords = {augmentative communication and control, brain-computer interfaces, neuro-muscular disorders}, issn = {1567-424X}, doi = {10.1145/1296843.1296845}, url = {http://www.ncbi.nlm.nih.gov/pubmed/16106662}, author = {Jonathan Wolpaw} } @article {3139, title = {Control of a two-dimensional movement signal by a noninvasive brain-computer interface in humans.}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {101}, year = {2004}, month = {12/2004}, pages = {17849{\textendash}17854}, abstract = {Brain-computer interfaces (BCIs) can provide communication and control to people who are totally paralyzed. BCIs can use noninvasive or invasive methods for recording the brain signals that convey the user{\textquoteright}s commands. Whereas noninvasive BCIs are already in use for simple applications, it has been widely assumed that only invasive BCIs, which use electrodes implanted in the brain, can provide multidimensional movement control of a robotic arm or a neuroprosthesis. We now show that a noninvasive BCI that uses scalp-recorded electroencephalographic activity and an adaptive algorithm can provide humans, including people with spinal cord injuries, with multidimensional point-to-point movement control that falls within the range of that reported with invasive methods in monkeys. In movement time, precision, and accuracy, the results are comparable to those with invasive BCIs. The adaptive algorithm used in this noninvasive BCI identifies and focuses on the electroencephalographic features that the person is best able to control and encourages further improvement in that control. The results suggest that people with severe motor disabilities could use brain signals to operate a robotic arm or a neuroprosthesis without needing to have electrodes implanted in their brains.}, keywords = {brain-machine interface, Electroencephalography}, issn = {0027-8424}, doi = {10.1073/pnas.0403504101}, url = {http://www.ncbi.nlm.nih.gov/pubmed/15585584}, author = {Jonathan Wolpaw and Dennis J. McFarland} } @article {3140, title = {Conversion of EEG activity into cursor movement by a brain-computer interface (BCI).}, journal = {IEEE transactions on neural systems and rehabilitation engineering : a publication of the IEEE Engineering in Medicine and Biology Society}, volume = {12}, year = {2004}, month = {09/2004}, pages = {331{\textendash}338}, abstract = {The Wadsworth electroencephalogram (EEG)-based brain-computer interface (BCI) uses amplitude in mu or beta frequency bands over sensorimotor cortex to control cursor movement. Trained users can move the cursor in one or two dimensions. The primary goal of this research is to provide a new communication and control option for people with severe motor disabilities. Currently, cursor movements in each dimension are determined 10 times/s by an empirically derived linear function of one or two EEG features (i.e., spectral bands from different electrode locations). This study used offline analysis of data collected during system operation to explore methods for improving the accuracy of cursor movement. The data were gathered while users selected among three possible targets by controlling vertical [i.e., one-dimensional (1-D)] cursor movement. The three methods analyzed differ in the dimensionality of the cursor movement [1-D versus two-dimensional (2-D)] and in the type of the underlying function (linear versus nonlinear). We addressed two questions: Which method is best for classification (i.e., to determine from the EEG which target the user wants to hit)? How does the number of EEG features affect the performance of each method? All methods reached their optimal performance with 10-20 features. In offline simulation, the 2-D linear method and the 1-D nonlinear method improved performance significantly over the 1-D linear method. The 1-D linear method did not do so. These offline results suggest that the 1-D nonlinear or the 2-D linear cursor function will improve online operation of the BCI system.}, keywords = {augmentative communication, Brain-computer interface (BCI), Electroencephalography, Feedback}, issn = {1534-4320}, doi = {10.1109/TNSRE.2004.834627}, url = {http://www.ncbi.nlm.nih.gov/pubmed/15473195}, author = {Fabiani, Georg E. and Dennis J. McFarland and Jonathan Wolpaw and Pfurtscheller, Gert} } @article {2269, title = {P300 for communication: Evidence from patients with amyotrophic lateral sclerosis (ALS).}, journal = {Biomedizinische Technik}, year = {2004}, author = {Mellinger, J{\"u}rgen and Nijboer, F and Pawelzik, H and Gerwin Schalk and Dennis J. McFarland and Theresa M Vaughan and Jonathan Wolpaw and Niels Birbaumer and Kuebler, A.} } @article {3144, title = {Brain-computer interface (BCI) operation: optimizing information transfer rates.}, journal = {Biological psychology}, volume = {63}, year = {2003}, month = {07/2003}, pages = {237{\textendash}251}, abstract = {People can learn to control mu (8-12 Hz) or beta (18-25 Hz) rhythm amplitude in the EEG recorded over sensorimotor cortex and use it to move a cursor to a target on a video screen. In the present version of the cursor movement task, vertical cursor movement is a linear function of mu or beta rhythm amplitude. At the same time the cursor moves horizontally from left to right at a fixed rate. A target occupies 50\% (2-target task) to 20\% (5-target task) of the right edge of the screen. The user{\textquoteright}s task is to move the cursor vertically so that it hits the target when it reaches the right edge. The goal of the present study was to optimize system performance. To accomplish this, we evaluated the impact on system performance of number of targets (i.e. 2-5) and trial duration (i.e. horizontal movement time from 1 to 4 s). Performance was measured as accuracy (percent of targets selected correctly) and also as bit rate (bits/min) (which incorporates, in addition to accuracy, speed and the number of possible targets). Accuracy declined as target number increased. At the same time, for six of eight users, four targets yielded the maximum bit rate. Accuracy increased as movement time increased. At the same time, the movement time with the highest bit rate varied across users from 2 to 4 s. These results indicate that task parameters such as target number and trial duration can markedly affect system performance. They also indicate that optimal parameter values vary across users. Selection of parameters suited both to the specific user and the requirements of the specific application is likely to be a key factor in maximizing the success of EEG-based communication and control.}, keywords = {augmentative communication, Electroencephalography, information, Learning, mu rhythm, operant conditioning, prosthesis, Rehabilitation, sensorimotor cortex}, issn = {0301-0511}, doi = {10.1016/S0301-0511(03)00073-5}, url = {http://www.ncbi.nlm.nih.gov/pubmed/12853169}, author = {Dennis J. McFarland and Sarnacki, William A. and Jonathan Wolpaw} } @article {3226, title = {Brain-computer interface technology: a review of the Second International Meeting.}, journal = {IEEE transactions on neural systems and rehabilitation engineering : a publication of the IEEE Engineering in Medicine and Biology Society}, volume = {11}, year = {2003}, month = {06/2003}, pages = {94{\textendash}109}, abstract = {This paper summarizes the Brain-Computer Interfaces for Communication and Control, The Second International Meeting, held in Rensselaerville, NY, in June 2002. Sponsored by the National Institutes of Health and organized by the Wadsworth Center of the New York State Department of Health, the meeting addressed current work and future plans in brain-computer interface (BCI) research. Ninety-two researchers representing 38 different research groups from the United States, Canada, Europe, and China participated. The BCIs discussed at the meeting use electroencephalographic activity recorded from the scalp or single-neuron activity recorded within cortex to control cursor movement, select letters or icons, or operate neuroprostheses. The central element in each BCI is a translation algorithm that converts electrophysiological input from the user into output that controls external devices. BCI operation depends on effective interaction between two adaptive controllers, the user who encodes his or her commands in the electrophysiological input provided to the BCI, and the BCI that recognizes the commands contained in the input and expresses them in device control. Current BCIs have maximum information transfer rates of up to 25 b/min. Achievement of greater speed and accuracy requires improvements in signal acquisition and processing, in translation algorithms, and in user training. These improvements depend on interdisciplinary cooperation among neuroscientists, engineers, computer programmers, psychologists, and rehabilitation specialists, and on adoption and widespread application of objective criteria for evaluating alternative methods. The practical use of BCI technology will be determined by the development of appropriate applications and identification of appropriate user groups, and will require careful attention to the needs and desires of individual users.}, keywords = {augmentative communication, Brain-computer interface (BCI), electroencephalography (EEG), Rehabilitation}, issn = {1534-4320}, doi = {10.1109/TNSRE.2003.814799}, url = {http://www.ncbi.nlm.nih.gov/pubmed/12899247}, author = {Theresa M Vaughan and Heetderks, William J. and Trejo, Leonard J. and Rymer, William Z. and Weinrich, Michael and Moore, Melody M. and K{\"u}bler, Andrea and Dobkin, Bruce H. and Niels Birbaumer and Emanuel Donchin and Wolpaw, Elizabeth Winter and Jonathan Wolpaw} } @article {3196, title = {Conditioned H-reflex increase persists after transection of the main corticospinal tract in rats.}, journal = {Journal of neurophysiology}, volume = {90}, year = {2003}, month = {11/2003}, pages = {3572{\textendash}3578}, abstract = {The brain shapes spinal cord function throughout life. Operant conditioning of the H-reflex, the electrical analog of the spinal stretch reflex (SSR), is a relatively simple model for exploring the spinal cord plasticity underlying this functional change and may provide a new method for modifying spinal cord reflexes after spinal cord injury. In response to an operant conditioning protocol, rats can gradually increase (i.e., up-training mode) or decrease (i.e., down-training mode) the soleus H-reflex. This study explored the effects of midthoracic transection of the ipsilateral lateral column (LC) (rubrospinal, vestibulospinal, and reticulospinal tracts), the dorsal column corticospinal tract (CST), or the dorsal column ascending tract (DA) on maintenance of an H-reflex increase that has already occurred. Rats were implanted with EMG electrodes in the right soleus muscle and a nerve-stimulating cuff on the right posterior tibial nerve. After initial (i.e., control) H-reflex size was determined, the rats were exposed for 50 days to the up-training mode, in which reward was given when the H-reflex was above a criterion value. H-reflex size gradually rose to 168 +/- 12\% (mean +/- SE) of its initial value. Each rat then received an LC, CST, or DA transection and continued under the up-training mode for 50 more days. None of the transections abolished the H-reflex increase. H-reflex size increased further to 197 +/- 19\% of its initial value and did not differ significantly among LC, CST, and DA rats (P > 0.78 by ANOVA). Although earlier studies show that the main CST is needed for acquisition of H-reflex up-training and down-training and for maintenance of down-training, this study shows that it is not needed for maintenance of up-training. It adds to the evidence that H-reflex conditioning changes the spinal cord and that the spinal cord plasticity associated with up-training is different from that associated with down-training.}, keywords = {Spinal Cord Injuries}, issn = {0022-3077}, doi = {10.1152/jn.00264.2003}, url = {http://www.ncbi.nlm.nih.gov/pubmed/12917382}, author = {Xiang Yang Chen and Lu Chen and Jonathan Wolpaw} } @article {3157, title = {Conduction velocity is inversely related to action potential threshold in rat motoneuron axons.}, journal = {Experimental brain research. Experimentelle Hirnforschung. Exp{\'e}rimentation c{\'e}r{\'e}brale}, volume = {150}, year = {2003}, month = {06/2003}, pages = {497{\textendash}505}, abstract = {Intra-axonal recordings were performed in ventral roots of rats in vitro to study the conduction velocity and firing threshold properties of motoneuron axons. Mean values +/- SD were 30.5+/-5.6 m/s for conduction velocity and 11.6+/-4.5 mV for the depolarization from the resting potential required to reach firing threshold (threshold depolarization). Conduction velocity varied inversely and significantly with threshold depolarization ( P=0.0002 by linear regression). This relationship was evident even after accounting for variation in conduction velocity associated with action potential amplitude, injected current amplitude, or body weight. Conduction velocity also varied inversely with the time to action potential onset during just-threshold current pulse injection. These data suggest that the time course of depolarization leading to action potential initiation contributes to the speed of conduction in motoneuron axons.}, keywords = {action potential, conduction velocity, intra-axonal recording, myelinated axon, threshold}, issn = {0014-4819}, doi = {10.1007/s00221-003-1475-8}, url = {http://www.ncbi.nlm.nih.gov/pubmed/12715118}, author = {Jonathan S. Carp and Tennissen, Ann M. and Jonathan Wolpaw} } @article {3142, title = {EEG-based communication and control: speed-accuracy relationships.}, journal = {Applied psychophysiology and biofeedback}, volume = {28}, year = {2003}, month = {09/2003}, pages = {217{\textendash}231}, abstract = {People can learn to control mu (8-12 Hz) or beta (18-25 Hz) rhythm amplitude in the EEG recorded over sensorimotor cortex and use it to move a cursor to a target on a video screen. In our current EEG-based brain-computer interface (BCI) system, cursor movement is a linear function of mu or beta rhythm amplitude. In order to maximize the participant{\textquoteright}s control over the direction of cursor movement, the intercept in this equation is kept equal to the mean amplitude of recent performance. Selection of the optimal slope, or gain, which determines the magnitude of the individual cursor movements, is a more difficult problem. This study examined the relationship between gain and accuracy in a 1-dimensional EEG-based cursor movement task in which individuals select among 2 or more choices by holding the cursor at the desired choice for a fixed period of time (i.e., the dwell time). With 4 targets arranged in a vertical column on the screen, large gains favored the end targets whereas smaller gains favored the central targets. In addition, manipulating gain and dwell time within participants produces results that are in agreement with simulations based on a simple theoretical model of performance. Optimal performance occurs when correct selection of targets is uniform across position. Thus, it is desirable to remove any trend in the function relating accuracy to target position. We evaluated a controller that is designed to minimize the linear and quadratic trends in the accuracy with which participants hit the 4 targets. These results indicate that gain should be adjusted to the individual participants, and suggest that continual online gain adaptation could increase the speed and accuracy of EEG-based cursor control.}, keywords = {Video Recording}, issn = {1090-0586}, doi = {10.1023/A:1024685214655}, url = {http://www.ncbi.nlm.nih.gov/pubmed/12964453}, author = {Dennis J. McFarland and Jonathan Wolpaw} } @article {3145, title = {Electroencephalographic(EEG)-based communication: EEG control versus system performance in humans.}, journal = {Neuroscience letters}, volume = {345}, year = {2003}, month = {07/2002}, pages = {89{\textendash}92}, abstract = {People can learn to control electroencephalographic (EEG) sensorimotor rhythm amplitude so as to move a cursor to select among choices on a computer screen. We explored the dependence of system performance on EEG control. Users moved the cursor to reach a target at one of four possible locations. EEG control was measured as the correlation (r(2)) between rhythm amplitude and target location. Performance was measured as accuracy (\% of targets hit) and as information transfer rate (bits/trial). The relationship between EEG control and accuracy can be approximated by a linear function that is constant for all users. The results facilitate offline predictions of the effects on performance of using different EEG features or combinations of features to control cursor movement.}, keywords = {augmentative communication, brain-computer interface, brain-machine interface, Electroencephalography, mu and beta rhythms, neuroprosthesis, Rehabilitation}, issn = {0304-3940}, doi = {10.1016/S0304-3940(03)00470-1}, url = {http://www.ncbi.nlm.nih.gov/pubmed/12821178}, author = {Sheikh, Hesham and Dennis J. McFarland and Sarnacki, William A. and Jonathan Wolpaw} } @article {3224, title = {EMG contamination of EEG: spectral and topographical characteristics.}, journal = {Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology}, volume = {114}, year = {2003}, month = {09/2003}, pages = {1580{\textendash}1593}, abstract = {OBJECTIVE: Electromyogram (EMG) contamination is often a problem in electroencephalogram (EEG) recording, particularly, for those applications such as EEG-based brain-computer interfaces that rely on automated measurements of EEG features. As an essential prelude to developing methods for recognizing and eliminating EMG contamination of EEG, this study defines the spectral and topographical characteristics of frontalis and temporalis muscle EMG over the entire scalp. It describes both average data and the range of individual differences. METHODS: In 25 healthy adults, signals from 64 scalp and 4 facial locations were recorded during relaxation and during defined (15, 30, or 70\% of maximum) contractions of frontalis or temporalis muscles. RESULTS: In the average data, EMG had a broad frequency distribution from 0 to >200 Hz. Amplitude was greatest at 20-30 Hz frontally and 40-80 Hz temporally. Temporalis spectra also showed a smaller peak around 20 Hz. These spectral components attenuated and broadened centrally. Even with weak (15\%) contraction, EMG was detectable (P<0.001) near the vertex at frequencies >12 Hz in the average data and >8 Hz in some individuals. CONCLUSIONS: Frontalis or temporalis muscle EMG recorded from the scalp has spectral and topographical features that vary substantially across individuals. EMG spectra often have peaks in the beta frequency range that resemble EEG beta peaks. SIGNIFICANCE: While EMG contamination is greatest at the periphery of the scalp near the active muscles, even weak contractions can produce EMG that obscures or mimics EEG alpha, mu, or beta rhythms over the entire scalp. Recognition and elimination of this contamination is likely to require recording from an appropriate set of peripheral scalp locations.}, keywords = {artifact, brain-computer interface, electroencephalogram, electromyogram, Rehabilitation}, issn = {1388-2457}, doi = {10.1016/S1388-2457(03)00093-2}, url = {http://www.ncbi.nlm.nih.gov/pubmed/12948787}, author = {Goncharova, I. I. and Dennis J. McFarland and Theresa M Vaughan and Jonathan Wolpaw} } @article {2165, title = {The Wadsworth Center brain-computer interface (BCI) research and development program.}, journal = {IEEE Trans Neural Syst Rehabil Eng}, volume = {11}, year = {2003}, month = {06/2003}, pages = {204-7}, abstract = {

Brain-computer interface (BCI) research at the Wadsworth Center has focused primarily on using electroencephalogram (EEG) rhythms recorded from the scalp over sensorimotor cortex to\ control\ cursor movement in one or two dimensions. Recent and current studies seek to improve the speed and accuracy of this\ control\ by improving the selection of signal features and their translation into device commands, by incorporating additional signal features, and by optimizing the adaptive interaction between the user and system. In addition, to facilitate the evaluation, comparison, and combination of alternative BCI methods, we have developed a general-purpose BCI system called BCI-2000 and have made it available to other research\ groups. Finally, in collaboration with several other\ groups, we are developing simple BCI applications and are testing their practicality and long-term value for people with severe motor disabilities.

}, keywords = {Academic Medical Centers, Adult, Algorithms, Artifacts, Brain, Brain Mapping, Electroencephalography, Evoked Potentials, Visual, Feedback, Humans, Middle Aged, Nervous System Diseases, Research, Research Design, User-Computer Interface, Visual Perception}, issn = {1534-4320}, doi = {10.1109/TNSRE.2003.814442}, url = {http://www.ncbi.nlm.nih.gov/pubmed/12899275}, author = {Jonathan Wolpaw and Dennis J. McFarland and Theresa M Vaughan and Gerwin Schalk} } @article {2268, title = {Brain-computer interfaces for communication and control.}, journal = {Clin Neurophysiol}, volume = {113}, year = {2002}, month = {06/2002}, pages = {767-91}, abstract = {

For many years people have speculated that electroencephalographic activity or other electrophysiological measures of brain function might provide a new non-muscular channel for sending messages and commands to the external world - a brain-computer interface (BCI). Over the past 15 years, productive BCI research programs have arisen. Encouraged by new understanding of brain function, by the advent of powerful low-cost computer equipment, and by growing recognition of the needs and potentials of people with disabilities, these programs concentrate on developing new augmentative communication and\ controltechnology for those with severe neuromuscular disorders, such as amyotrophic lateral sclerosis, brainstem stroke, and spinal cord injury. The immediate goal is to provide these users, who may be completely paralyzed, or {\textquoteright}locked in{\textquoteright}, with basic communication capabilities so that they can express their wishes to caregivers or even operate word processing programs or neuroprostheses. Present-day BCIs determine the intent of the user from a variety of different electrophysiological signals. These signals include slow cortical potentials, P300 potentials, and mu or beta rhythms recorded from the scalp, and cortical neuronal activity recorded by implanted electrodes. They are translated in real-time into commands that operate a computer display or other device. Successful operation requires that the user encode commands in these signals and that the BCI derive the commands from the signals. Thus, the user and the BCI system need to adapt to each other both initially and continually so as to ensure stable performance. Current BCIs have maximum information transfer rates up to 10-25bits/min. This limited capacity can be valuable for people whose severe disabilities prevent them from using conventional augmentative communication methods. At the same time, many possible applications of BCI technology, such as neuroprosthesis\ control, may require higher information transfer rates. Future progress will depend on: recognition that BCI research and development is an interdisciplinary problem, involving neurobiology, psychology, engineering, mathematics, and computer science; identification of those signals, whether evoked potentials, spontaneous rhythms, or neuronal firing rates, that users are best able to\ control\ independent of activity in conventional motor output pathways; development of training methods for helping users to gain and maintain that\ control; delineation of the best algorithms for translating these signals into device commands; attention to the identification and elimination of artifacts such as electromyographic and electro-oculographic activity; adoption of precise and objective procedures for evaluating BCI performance; recognition of the need for long-term as well as short-term assessment of BCI performance; identification of appropriate BCI applications and appropriate matching of applications and users; and attention to factors that affect user acceptance of augmentative technology, including ease of use, cosmesis, and provision of those communication and\ control\ capacities that are most important to the user. Development of BCI technology will also benefit from greater emphasis on peer-reviewed research publications and avoidance of the hyperbolic and often misleading media attention that tends to generate unrealistic expectations in the public and skepticism in other researchers. With adequate recognition and effective engagement of all these issues, BCI systems could eventually provide an important new communication and\ control\ option for those with motor disabilities and might also give those without disabilities a supplementary\ control\ channel or a\ control\ channel useful in special circumstances.

}, keywords = {Brain Diseases, Communication Aids for Disabled, Computer Systems, Electroencephalography, Humans, User-Computer Interface}, issn = {1388-2457}, doi = {10.1016/S1388-2457(02)00057-3}, url = {http://www.ncbi.nlm.nih.gov/pubmed/12048038}, author = {Jonathan Wolpaw and Niels Birbaumer and Dennis J. McFarland and Pfurtscheller, Gert and Theresa M Vaughan} } @article {3159, title = {Corticospinal tract transection prevents operantly conditioned H-reflex increase in rats.}, journal = {Experimental brain research. Experimentelle Hirnforschung. Exp{\'e}rimentation c{\'e}r{\'e}brale}, volume = {144}, year = {2002}, month = {05/2002}, pages = {88{\textendash}94}, abstract = {Operant conditioning of the H-reflex, the electrical analog of the spinal stretch reflex, in freely moving rats is a relatively simple model for studying long-term supraspinal control over spinal cord function. Motivated by food reward, rats can gradually increase (i.e., up-condition) or decrease (i.e., down-condition) the soleus H-reflex. Earlier work showed that corticospinal tract transection prevents acquisition and maintenance of H-reflex down-conditioning while transection of other major spinal cord tracts does not. This study explores the effects on acquisition of up-conditioning of the right soleus H-reflex of mid-thoracic transection of: the right lateral column (LC, five rats) (containing the rubrospinal, vestibulospinal, and reticulospinal tracts); the entire dorsal column (DC, six rats) [containing the main corticospinal tract (CST) and the dorsal ascending tract (DA)]; the CST alone (five rats); or the DA alone (seven rats). After initial (i.e., control) H-reflex amplitude was determined, the rat was exposed for 50 days to the up-conditioning mode in which reward was given when the H-reflex was above a criterion value. H-reflex amplitude at the end of up-conditioning was compared to initial H-reflex amplitude. An increase > or =20\% was defined as successful up-conditioning. In intact rats, H-reflex amplitude at the end of up-conditioning averaged 164\% (+/-10\%, SE), and 81\% were successful. In the present study, LC and DA rats were similar to intact rats in final H-reflex amplitude and percent successful. In contrast, results for DC and CST rats were significantly different from those of intact rats. In the six DC rats, final H-reflex amplitude averaged 105\% (+/-3)\% of control and none was successful; and in the five CST rats, final H-reflex amplitude averaged 94\% (+/-3)\% and none was successful. The results indicate that the main CST, located in the dorsal column, is essential for H-reflex up-conditioning as it is for down-conditioning, while the dorsal column ascending tract and the ipsilateral lateral column (containing the main rubrospinal, vestibulospinal, and reticulospinal tracts) do not appear to be essential.}, keywords = {dorsal column, lateral column, Learning, plasticity, spinal cord injury}, issn = {0014-4819}, doi = {10.1007/s00221-002-1026-8}, url = {http://www.ncbi.nlm.nih.gov/pubmed/11976762}, author = {Xiang Yang Chen and Jonathan S. Carp and Lu Chen and Jonathan Wolpaw} } @article {3197, title = {Corticospinal tract transection reduces H-reflex circadian rhythm in rats.}, journal = {Brain research}, volume = {942}, year = {2002}, month = {06/2002}, pages = {101{\textendash}108}, abstract = {In freely moving rats and monkeys, H-reflex amplitude displays a marked circadian variation without change in background motoneuron tone. In rats, the H-reflex is largest around noon and smallest around midnight. The present study evaluated in rats the effects on this rhythm of calibrated contusions of mid-thoracic spinal cord and mid-thoracic transection of specific spinal cord pathways. In 33 control rats, rhythm amplitude averaged 29.0(+/-2.6 S.E.)\% of H-reflex amplitude. Contusion injuries at T8-9 that destroyed 53-88\% of the white matter significantly reduced the rhythm to 18.9(+/-2.4)\% of H-reflex amplitude. Transection of the ipsilateral lateral column, which contains the rubrospinal, vestibulospinal, and reticulospinal tracts, or bilateral transection of the dorsal column ascending tract did not affect rhythm amplitude or phase. In contrast, bilateral transection of the main corticospinal tract significantly reduced the rhythm to 14.7(+/-6.6)\%. These results indicate that the H-reflex circadian rhythm depends in part on descending influence from the brain and that this influence is conveyed by the main corticospinal tract.}, keywords = {circadian rhythms, corticospinal tract, diurnal rhythm, H-Reflex, rat, spinal cord injury}, issn = {0006-8993}, doi = {10.1016/S0006-8993(02)02702-6}, url = {http://www.ncbi.nlm.nih.gov/pubmed/12031858}, author = {Xiang Yang Chen and Lu Chen and Jonathan Wolpaw and Jakeman, Lyn B.} } @article {3206, title = {Memory in neuroscience: rhetoric versus reality.}, journal = {Behavioral and cognitive neuroscience reviews}, volume = {1}, year = {2002}, month = {06/2002}, pages = {130{\textendash}163}, abstract = {The central point of this article is that the concept of memory as information storage in the brain is inadequate for and irrelevant to understanding the nervous system. Beginning from the sensorimotor hypothesis that underlies neuroscience{\textendash}that the entire function of the nervous system is to connect experience to appropriate behavior{\textendash}the paper defines memories as sequences of events that connect remote experience to present behavior. Their essential components are (a) persistent events that bridge the time from remote experience to present behavior and (b) junctional events in which connections from remote experience and recent experience merge to produce behavior. The sequences comprising even the simplest memories are complex. This is both necessary{\textendash}to preserve previously learned behaviors{\textendash}and inevitable{\textendash}due to secondary activity-driven plasticity. This complexity further highlights the inadequacy of the information storage concept and the importance of extreme simplicity in models used to study memory.}, keywords = {Psychological Theory}, issn = {1534-5823}, doi = {10.1177/1534582302001002003}, url = {http://www.ncbi.nlm.nih.gov/pubmed/17715590}, author = {Jonathan Wolpaw} } @article {3198, title = {Probable corticospinal tract control of spinal cord plasticity in the rat.}, journal = {Journal of neurophysiology}, volume = {87}, year = {2002}, month = {02/2002}, pages = {645{\textendash}652}, abstract = {Descending activity from the brain shapes spinal cord reflex function throughout life, yet the mechanisms responsible for this spinal cord plasticity are poorly understood. Operant conditioning of the H-reflex, the electrical analogue of the spinal stretch reflex, is a simple model for investigating these mechanisms. An earlier study in the Sprague-Dawley rat showed that acquisition of an operantly conditioned decrease in the soleus H-reflex is not prevented by mid-thoracic transection of the ipsilateral lateral column (LC), which contains the rubrospinal, reticulospinal, and vestibulospinal tracts, and is prevented by transection of the dorsal column, which contains the main corticospinal tract (CST) and the dorsal column ascending tract (DA). The present study explored the effects of CST or DA transection on acquisition of an H-reflex decrease, and the effects of LC, CST, or DA transection on maintenance of an established decrease. CST transection prior to conditioning prevented acquisition of H-reflex decrease, while DA transection did not do so. CST transection after H-reflex decrease had been acquired led to gradual loss of the decrease over 10 days, and resulted in an H-reflex that was significantly larger than the original, naive H-reflex. In contrast, LC or DA transection after H-reflex decrease had been acquired did not affect maintenance of the decrease. These results, in combination with the earlier study, strongly imply that in the rat the corticospinal tract (CST) is essential for acquisition and maintenance of operantly conditioned decrease in the H-reflex and that other major spinal cord pathways are not essential. This previously unrecognized aspect of CST function gives insight into the processes underlying acquisition and maintenance of motor skills and could lead to novel methods for inducing, guiding, and assessing recovery of function after spinal cord injury.}, keywords = {Spinal Cord Injuries}, issn = {0022-3077}, doi = {10.1152/jn.00391.2001}, url = {http://www.ncbi.nlm.nih.gov/pubmed/11826033}, author = {Xiang Yang Chen and Jonathan Wolpaw} } @article {2164, title = {Temporal transformation of multiunit activity improves identification of single motor units.}, journal = {J Neurosci Methods}, volume = {114}, year = {2002}, month = {02/2002}, pages = {87-98}, abstract = {

This report describes a temporally based method for identifying repetitive firing of motor units. This\ approach\ is ideally suited to spike trains with negative serially correlated inter-spike intervals (ISIs). It can also be applied to spike trains in which ISIs exhibit little serial correlation if their coefficient of variation (COV) is sufficiently low. Using a novel application of the Hough transform, this method (i.e. the modified Hough transform (MHT)) maps motor unit action potential (MUAP) firing times into a feature space with ISI and offset (defined as the latency from an arbitrary starting time to the first MUAP in the train) as dimensions. Each MUAP firing time corresponds to a pattern in the feature space that represents all possible MUAP trains with a firing at that time. Trains with stable ISIs produce clusters in the feature space, whereas randomly firing trains do not. The MHT provides a direct estimate of mean firing rate and its variability for the entire data segment, even if several individual MUAPs are obscured by firings from other motor units. Addition of this method to a shape-based classification\ approach\ markedly improved rejection of false positives using simulated data and identified spike trains in whole muscle electromyographic recordings from rats. The relative independence of the MHT from the need to correctly classify individual firings permits a global description of stable repetitive firing behavior that is complementary to shape-based approaches to MUAP classification.

}, keywords = {Action Potentials, Animals, Electromyography, H-Reflex, Motor Neurons, Muscle, Skeletal, Rats, Signal Processing, Computer-Assisted}, issn = {0165-0270}, doi = {10.1016/S0165-0270(01)00517-9}, url = {http://www.ncbi.nlm.nih.gov/pubmed/11850043}, author = {Gerwin Schalk and Jonathan S. Carp and Jonathan Wolpaw} } @article {3229, title = {Activity-dependent spinal cord plasticity in health and disease.}, journal = {Annual review of neuroscience}, volume = {24}, year = {2001}, month = {03/2001}, pages = {807{\textendash}843}, abstract = {Activity-dependent plasticity occurs in the spinal cord throughout life. Driven by input from the periphery and the brain, this plasticity plays an important role in the acquisition and maintenance of motor skills and in the effects of spinal cord injury and other central nervous system disorders. The responses of the isolated spinal cord to sensory input display sensitization, long-term potentiation, and related phenomena that contribute to chronic pain syndromes; they can also be modified by both classical and operant conditioning protocols. In animals with transected spinal cords and in humans with spinal cord injuries, treadmill training gradually modifies the spinal cord so as to improve performance. These adaptations by the isolated spinal cord are specific to the training regimen and underlie new approaches to restoring function after spinal cord injury. Descending inputs from the brain that occur during normal development, as a result of supraspinal trauma, and during skill acquisition change the spinal cord. The early development of adult spinal cord reflex patterns is driven by descending activity; disorders that disrupt descending activity later in life gradually change spinal cord reflexes. Athletic training, such as that undertaken by ballet dancers, is associated with gradual alterations in spinal reflexes that appear to contribute to skill acquisition. Operant conditioning protocols in animals and humans can produce comparable reflex changes and are associated with functional and structural plasticity in the spinal cord, including changes in motoneuron firing threshold and axonal conduction velocity, and in synaptic terminals on motoneurons. The corticospinal tract has a key role in producing this plasticity. Behavioral changes produced by practice or injury reflect the combination of plasticity at multiple spinal cord and supraspinal sites. Plasticity at multiple sites is both necessary-to insure continued performance of previously acquired behaviors-and inevitable-due to the ubiquity of the capacity for activity-dependent plasticity in the central nervous system. Appropriate induction and guidance of activity-dependent plasticity in the spinal cord is an essential component of new therapeutic approaches aimed at maximizing function after spinal cord injury or restoring function to a newly regenerated spinal cord. Because plasticity in the spinal cord contributes to skill acquisition and because the spinal cord is relatively simple and accessible, this plasticity is a logical and practical starting point for studying the acquisition and maintenance of skilled behaviors.}, keywords = {behavior, conditioning, Learning, Memory, Rehabilitation, spinal cord injury}, issn = {0147-006X}, doi = {10.1146/annurev.neuro.24.1.807}, url = {http://www.ncbi.nlm.nih.gov/pubmed/11520919}, author = {Jonathan Wolpaw and Tennissen, A. M.} } @article {3230, title = {Brain-computer communication: unlocking the locked in.}, journal = {Psychological bulletin}, volume = {127}, year = {2001}, month = {05/2001}, pages = {358{\textendash}375}, abstract = {With the increasing efficiency of life-support systems and better intensive care, more patients survive severe injuries of the brain and spinal cord. Many of these patients experience locked-in syndrome: The active mind is locked in a paralyzed body. Consequently, communication is extremely restricted or impossible. A muscle-independent communication channel overcomes this problem and is realized through a brain-computer interface, a direct connection between brain and computer. The number of technically elaborated brain-computer interfaces is in contrast with the number of systems used in the daily life of locked-in patients. It is hypothesized that a profound knowledge and consideration of psychological principles are necessary to make brain-computer interfaces feasible for locked-in patients.}, keywords = {User-Computer Interface}, issn = {0033-2909}, doi = {10.1037/0033-2909.127.3.358}, url = {http://www.ncbi.nlm.nih.gov/pubmed/11393301}, author = {K{\"u}bler, A. and Kotchoubey, B. and Kaiser, J. and Jonathan Wolpaw and Niels Birbaumer} } @article {3162, title = {Effects of chronic nerve cuff and intramuscular electrodes on rat triceps surae motor units.}, journal = {Neuroscience letters}, volume = {312}, year = {2001}, month = {10/2001}, pages = {1{\textendash}4}, abstract = {In order to assess the long-term effects of implanted electrodes on motor unit properties, we studied triceps surae (TS) motor units in rats implanted for 3-10 months with a tibial nerve cuff electrode for H-reflex elicitation and intramuscular electrodes for recording TS electromyographic activity. Motor units with sag from implanted rats displayed greater tetanic force than those from unimplanted rats. Motor units without sag had shorter twitch contraction times. This disrupted the relationship between sag and contraction time that was always present in unimplanted rats. These differences were consistent with a small degree of muscle denervation and subsequent reinnervation. Further analyses ascribed this effect to the nerve cuff rather than to the intramuscular electrodes. Comparable changes in motor unit properties may occur in humans with implanted nerve cuffs.}, keywords = {chronic recording, contraction time, H-Reflex, implanted electrodes, motor units, nerve cuff, reinnervation, sag}, issn = {0304-3940}, doi = {10.1016/S0304-3940(01)02183-8}, url = {http://www.ncbi.nlm.nih.gov/pubmed/11578831}, author = {Jonathan S. Carp and Xiang Yang Chen and Sheikh, H. and Jonathan Wolpaw} } @article {3161, title = {Motor unit properties after operant conditioning of rat H-reflex.}, journal = {Experimental brain research. Experimentelle Hirnforschung. Exp{\'e}rimentation c{\'e}r{\'e}brale}, volume = {140}, year = {2001}, month = {10/2001}, pages = {382{\textendash}386}, abstract = {Operant conditioning of the H-reflex produces plasticity at several sites in the spinal cord, including the motoneuron. This study assessed whether this spinal cord plasticity is accompanied by changes in motor unit contractile properties. Thirty-one adult male Sprague-Dawley rats implanted for chronic recording of triceps surae electromyographic activity and H-reflex elicitation were exposed for at least 40 days to HRup or HRdown training, in which reward occurred when the H-reflex was greater than (12 HRup rats) or less than (12 HRdown rats) a criterion value, or continued under the control mode in which the H-reflex was simply measured (7 HRcon rats). At the end of H-reflex data collection, rats were anesthetized and the contractile properties of 797 single triceps surae motor units activated by intraaxonal (or intramyelin) current injection were determined. Motor units were classified as S, FR, Fint, or FF on the basis of sag and fatigue properties. Maximum tetanic force and twitch contraction time were also measured. HRdown rats exhibited a significant increase in the fatigue index of fast-twitch motor units. This resulted in a significant decrease in the percentage of Fint motor units and a significant increase in that of FR motor units. HRup conditioning had no effect on fatigue index. Neither HRup nor HRdown conditioning affected maximum tetanic force or twitch contraction time. These data are consistent with the hypothesis that conditioning mode-specific change in motoneuron firing patterns causes activity-dependent change in muscle properties.}, keywords = {H-Reflex, motor unit type, operant conditioning, plasticity, triceps surae}, issn = {0014-4819}, doi = {10.1007/s002210100830}, url = {http://www.ncbi.nlm.nih.gov/pubmed/11681314}, author = {Jonathan S. Carp and Xiang Yang Chen and Sheikh, H. and Jonathan Wolpaw} } @article {3163, title = {Operant conditioning of rat H-reflex affects motoneuron axonal conduction velocity.}, journal = {Experimental brain research. Experimentelle Hirnforschung. Exp{\'e}rimentation c{\'e}r{\'e}brale}, volume = {136}, year = {2001}, month = {01/2001}, pages = {269{\textendash}273}, abstract = {This study assessed the effects of operant conditioning of the H-reflex on motoneuron axonal conduction velocity in the rat. After measurement of the control H-reflex size, rats were either exposed for at least 40 days to the HRup or HRdown conditioning mode, in which reward occurred only if the soleus H-reflex was greater than (HRup mode) or less than (HRdown mode) a criterion or continued under the control condition (HRcon mode) in which the H-reflex was simply measured. We then measured axonal conduction velocity of triceps surae motor units of HRup, HRdown, and HRcon rats by stimulating the axon in the ventral root and recording from the tibial nerve. Conduction velocity was 8\% less in successful HRdown rats than in HRcon rats (P=0.02). Conduction velocity in HRup rats and unsuccessful HRdown rats was not significantly different from that in HRcon rats. Since recording bypassed the intra-spinal portion of the motoneuron, the change was clearly in the axon. This decrease was similar to the 6\% decrease previously found in successful HRdown monkeys. Unsuccessful HRdown rats and monkeys did not show this decrease. This result suggests that the mechanism of HRdown conditioning is similar in rats and monkeys and provides further support for the hypothesis that HRdown conditioning decreases motoneuron excitability by producing a positive shift in firing threshold. While traditional theories of learning emphasize synaptic plasticity, neuronal plasticity may also contribute to operantly conditioned behavioral changes.}, keywords = {conduction velocity, H-Reflex, motoneuron, plasticity, Spinal Cord}, issn = {0014-4819}, doi = {10.1007/s002210000608}, url = {http://www.ncbi.nlm.nih.gov/pubmed/11206290}, author = {Jonathan S. Carp and Xiang Yang Chen and Sheikh, H. and Jonathan Wolpaw} } @article {3233, title = {Operant conditioning of rat H-reflex: effects on mean latency and duration.}, journal = {Experimental brain research. Experimentelle Hirnforschung. Exp{\'e}rimentation c{\'e}r{\'e}brale}, volume = {136}, year = {2001}, month = {01/2001}, pages = {274{\textendash}279}, abstract = {We are currently studying the mechanisms of operantly conditioned changes in the H-reflex in the rat. Primate data suggest that H-reflex decrease is due to a positive shift in motoneuron firing threshold and a small decrease in the monosynaptic excitatory postsynaptic potential (EPSP), and that increase might be due to change in group-I oligosynaptic (especially disynaptic) input. To further evaluate the possibility of conditioned change in oligosynaptic input, we compared the mean latency (i.e., the average latency of the entire H-reflex) and the duration of control (i.e., pre-conditioning) H-reflexes with those of H-reflexes after up-conditioning or down-conditioning. Up-conditioning was associated with small, statistically significant increases in H-reflex mean latency [+0.11+/-0.05 (+/-SE) ms] and duration (+0.32+/-0.16 ms). The mean latency of the H-reflex increase (i.e., the part added to the H-reflex by up-conditioning) was 0.28+/-0.14 (+/-SE) ms greater than that of the control H-reflex. Down-conditioning had no significant effect on mean latency or duration. While these results indicate that operant conditioning does not greatly change H-reflex mean latency or duration, the effects detected with up-conditioning are consistent with the hypothesis that decreased inhibition, or increased excitation, by homonymous and heteronymous group-I oligosynaptic input contributes to the H-reflex increase produced by up-conditioning. Several other mechanisms might also account for these small effects.}, keywords = {conditioning, H-Reflex, Memory, plasticity, Spinal Cord}, issn = {0014-4819}, doi = {10.1007/s002210000609}, url = {http://www.ncbi.nlm.nih.gov/pubmed/11206291}, author = {Jonathan Wolpaw and Xiang Yang Chen} } @article {3232, title = {Short-Term and medium-term effects of spinal cord tract transections on soleus H-reflex in freely moving rats.}, journal = {Journal of neurotrauma}, volume = {18}, year = {2001}, month = {03/2001}, pages = {313{\textendash}327}, abstract = {Spinal cord function is normally influenced by descending activity from supraspinal structures. When injury removes or distorts this influence, function changes and spasticity and other disabling problems eventually appear. Understanding how descending activity affects spinal cord function could lead to new means for inducing, guiding, and assessing recovery after injury. In this study, we investigated the short-term and medium-term effects of spinal cord bilateral dorsal column (DC), unilateral (ipsilateral) lateral column (LC), bilateral dorsal column ascending tract (DA), or bilateral dorsal column corticospinal tract (CST) transection at vertebral level T8-T9 on the soleus H-reflex in freely moving rats. Data were collected continuously for 10-20 days before and for 20-155 days after bilateral DC (13 rats), DA (10 rats), CST (eight rats), or ipsilateral LC (seven rats) transection. Histological examination showed that transections were 98(+/- 3 SD)\% complete for DC rats, 80(+/- 20)\% complete for LC rats, 91(+/- 13 SD)\% complete for DA rats, and 95(+/-13)\% complete for CST rats. LC, CST, and DA transections produced an immediate (i.e., first-day) increase in H-reflex amplitude. LC transection also produced a small decrease in background activity in the first few posttransection days. Other than this small decrease, none of the transections produced evidence for the phenomenon of spinal shock. For all transections, all measures returned to or neared pretransection values within 2 weeks. DA and LC transections were associated with modest increase in H-reflex amplitude 1-3 months after transection. These medium-term effects must be taken into account when assessing transection effects on operant conditioning of the H-reflex. At the same time, the results are consistent with other evidence that, while H-reflex rate dependence and H-reflex operant conditioning are sensitive measures of spinal cord injury, the H-reflex itself is not.}, keywords = {corticospinal tract, dorsal column, dorsal column ascending tract, lateral column, rat, soleus activity, spinal cord injury}, issn = {0897-7151}, doi = {10.1089/08977150151070973}, url = {http://www.ncbi.nlm.nih.gov/pubmed/11284551}, author = {Xiang Yang Chen and Feng-Chen, K. C. and Lu Chen and Stark, D. M. and Jonathan Wolpaw} } @article {3228, title = {Taking sides: corticospinal tract plasticity during development.}, journal = {Neurology}, volume = {57}, year = {2001}, month = {11/2001}, pages = {1530{\textendash}1531}, keywords = {Pyramidal Tracts}, issn = {0028-3878}, doi = {10.1212/WNL.57.9.1530}, url = {http://www.ncbi.nlm.nih.gov/pubmed/11706084}, author = {Jonathan Wolpaw and Kaas, J. H.} } @article {3231, title = {Time course of H-reflex conditioning in the rat.}, journal = {Neuroscience letters}, volume = {302}, year = {2001}, month = {04/2001}, pages = {85{\textendash}88}, abstract = {This study sought to define the course of operantly conditioned change in the rat soleus H-reflex and to determine whether, like H-reflex conditioning and spinal stretch reflex conditioning in the monkey, it develops in distinct phases. Data from 33 rats in which the right soleus H-reflex was trained up (i.e. HRup mode) and 38 in which it was trained down (i.e. HRdown mode) were averaged to define the courses of H-reflex increase and decrease. In HRup rats, the H-reflex showed a large phase I increase within the first 2 days followed by gradual phase II increase that continued for weeks. In HRdown rats, the H-reflex appeared to show a small phase I decrease and then showed a gradual phase II decrease over weeks. In combination with other recent work, the data suggest that H-reflex conditioning begins with a rapid mode-appropriate alteration in corticospinal tract influence over the spinal arc of the H-reflex, which causes phase I change, and that the continuation of this altered influence induces gradual spinal cord plasticity that is responsible for phase II change. The results further establish the similarity of H-reflex conditioning in primates and rats. Thus, they encourage efforts to produce a single coherent model of the phenomenon based on data from the two species and indicate the potential clinical relevance of the rat data.}, keywords = {conditioning, Learning, Memory, plasticity, rat, Reflex, Spinal Cord}, issn = {0304-3940}, doi = {10.1016/S0304-3940(01)01658-5}, url = {http://www.ncbi.nlm.nih.gov/pubmed/11290393}, author = {Xiang Yang Chen and Lu Chen and Jonathan Wolpaw} } @article {3235, title = {Brain-computer interface research at the Wadsworth Center.}, journal = {IEEE transactions on rehabilitation engineering : a publication of the IEEE Engineering in Medicine and Biology Society}, volume = {8}, year = {2000}, month = {06/2000}, pages = {222{\textendash}226}, abstract = {Studies at the Wadsworth Center over the past 14 years have shown that people with or without motor disabilities can learn to control the amplitude of mu or beta rhythms in electroencephalographic (EEG) activity recorded from the scalp over sensorimotor cortex and can use that control to move a cursor on a computer screen in one or two dimensions. This EEG-based brain-computer interface (BCI) could provide a new augmentative communication technology for those who are totally paralyzed or have other severe motor impairments. Present research focuses on improving the speed and accuracy of BCI communication.}, keywords = {User-Computer Interface}, issn = {1063-6528}, doi = {10.1109/86.847823}, url = {http://www.ncbi.nlm.nih.gov/pubmed/10896194}, author = {Jonathan Wolpaw and Dennis J. McFarland and Theresa M Vaughan} } @article {2163, title = {Brain-computer interface technology: a review of the first international meeting.}, journal = {IEEE Trans Rehabil Eng}, volume = {8}, year = {2000}, month = {06/2000}, pages = {164-73}, abstract = {

Over the past decade, many laboratories have begun to explore brain-computer interface (BCI) technology as a radically new communication option for those with neuromuscular impairments that prevent them from using conventional augmentative communication methods. BCI{\textquoteright}s provide these users with communication channels that do not depend on peripheral nerves and muscles. This article summarizes the first international meeting devoted to BCI research and development. Current BCI{\textquoteright}s use electroencephalographic (EEG) activity recorded at the scalp or single-unit activity recorded from within cortex to control cursor movement, select letters or icons, or operate a neuroprosthesis. The central element in each BCI is a translation algorithm that converts electrophysiological input from the user into output that controls external devices. BCI operation depends on effective interaction between two adaptive controllers, the user who encodes his or her commands in the electrophysiological input provided to the BCI, and the BCI which recognizes the commands contained in the input and expresses them in device control. Current BCI{\textquoteright}s have maximum information transfer rates of 5-25 b/min. Achievement of greater speed and accuracy depends on improvements in signal processing, translation algorithms, and user training. These improvements depend on increased interdisciplinary cooperation between neuroscientists, engineers, computer programmers, psychologists, and rehabilitation specialists, and on adoption and widespread application of objective methods for evaluating alternative methods. The practical use of BCI technology depends on the development of appropriate applications, identification of appropriate user groups, and careful attention to the needs and desires of individual users. BCI research and development will also benefit from greater emphasis on peer-reviewed publications, and from adoption of standard venues for presentations and discussion.

}, keywords = {Algorithms, Cerebral Cortex, Communication Aids for Disabled, Disabled Persons, Electroencephalography, Evoked Potentials, Humans, Neuromuscular Diseases, Signal Processing, Computer-Assisted, User-Computer Interface}, issn = {1063-6528}, doi = {10.1109/TRE.2000.847807}, url = {http://www.ncbi.nlm.nih.gov/pubmed/10896178}, author = {Jonathan Wolpaw and Niels Birbaumer and Heetderks, W J and Dennis J. McFarland and Peckham, P H and Gerwin Schalk and Emanuel Donchin and Quatrano, L A and Robinson, C J and Theresa M Vaughan} } @article {3236, title = {Brain-computer interface technology: a review of the first international meeting.}, journal = {IEEE transactions on rehabilitation engineering : a publication of the IEEE Engineering in Medicine and Biology Society}, volume = {8}, year = {2000}, month = {06/2000}, pages = {164{\textendash}173}, abstract = {Over the past decade, many laboratories have begun to explore brain-computer interface (BCI) technology as a radically new communication option for those with neuromuscular impairments that prevent them from using conventional augmentative communication methods. BCI{\textquoteright}s provide these users with communication channels that do not depend on peripheral nerves and muscles. This article summarizes the first international meeting devoted to BCI research and development. Current BCI{\textquoteright}s use electroencephalographic (EEG) activity recorded at the scalp or single-unit activity recorded from within cortex to control cursor movement, select letters or icons, or operate a neuroprosthesis. The central element in each BCI is a translation algorithm that converts electrophysiological input from the user into output that controls external devices. BCI operation depends on effective interaction between two adaptive controllers, the user who encodes his or her commands in the electrophysiological input provided to the BCI, and the BCI which recognizes the commands contained in the input and expresses them in device control. Current BCI{\textquoteright}s have maximum information transfer rates of 5-25 b/min. Achievement of greater speed and accuracy depends on improvements in signal processing, translation algorithms, and user training. These improvements depend on increased interdisciplinary cooperation between neuroscientists, engineers, computer programmers, psychologists, and rehabilitation specialists, and on adoption and widespread application of objective methods for evaluating alternative methods. The practical use of BCI technology depends on the development of appropriate applications, identification of appropriate user groups, and careful attention to the needs and desires of individual users. BCI research and development will also benefit from greater emphasis on peer-reviewed publications, and from adoption of standard venues for presentations and discussion.}, keywords = {augmentative communication, Brain-computer interface (BCI), electroencephalography (EEG)}, issn = {1063-6528}, doi = {10.1109/TRE.2000.847807}, url = {http://www.ncbi.nlm.nih.gov/pubmed/10896178}, author = {Jonathan Wolpaw and Niels Birbaumer and Heetderks, W. J. and Dennis J. McFarland and Peckham, P. H. and Gerwin Schalk and Emanuel Donchin and Quatrano, L. A. and Robinson, C. J. and Theresa M Vaughan} } @article {3234, title = {EEG-based communication: presence of an error potential.}, journal = {Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology}, volume = {111}, year = {2000}, month = {12/2000}, pages = {2138{\textendash}2144}, abstract = {EEG-based communication could be a valuable new augmentative communication technology for those with severe motor disabilities. Like all communication methods, it faces the problem of errors in transmission. In the Wadsworth EEG-based brain-computer interface (BCI) system, subjects learn to use mu or beta rhythm amplitude to move a cursor to targets on a computer screen. While cursor movement is highly accurate in trained subjects, it is not perfect.}, keywords = {augmentative communication, brain-computer interface, Electroencephalography, error potential, error related negativity, event related potential, mu rhythm, Rehabilitation, sensorimotor cortex}, issn = {1388-2457}, doi = {10.1016/S1388-2457(00)00457-0}, url = {http://www.ncbi.nlm.nih.gov/pubmed/11090763}, author = {Gerwin Schalk and Jonathan Wolpaw and Dennis J. McFarland and Pfurtscheller, G.} } @article {3237, title = {Emerging concepts in the pathophysiology of recovery from neonatal brachial plexus injury.}, journal = {Neurology}, volume = {55}, year = {2000}, month = {07/2000}, pages = {5{\textendash}6}, keywords = {Infant, Newborn}, issn = {0028-3878}, doi = {10.1212/WNL.55.1.5}, url = {http://www.ncbi.nlm.nih.gov/pubmed/10891895}, author = {Noetzel, M. J. and Jonathan Wolpaw} } @article {3238, title = {Mu and beta rhythm topographies during motor imagery and actual movements.}, journal = {Brain topography}, volume = {12}, year = {2000}, month = {03/2000}, pages = {177{\textendash}186}, abstract = {People can learn to control the 8-12 Hz mu rhythm and/or the 18-25 Hz beta rhythm in the EEG recorded over sensorimotor cortex and use it to control a cursor on a video screen. Subjects often report using motor imagery to control cursor movement, particularly early in training. We compared in untrained subjects the EEG topographies associated with actual hand movement to those associated with imagined hand movement. Sixty-four EEG channels were recorded while each of 33 adults moved left- or right-hand or imagined doing so. Frequency-specific differences between movement or imagery and rest, and between right- and left-hand movement or imagery, were evaluated by scalp topographies of voltage and r spectra, and principal component analysis. Both movement and imagery were associated with mu and beta rhythm desynchronization. The mu topographies showed bilateral foci of desynchronization over sensorimotor cortices, while the beta topographies showed peak desynchronization over the vertex. Both mu and beta rhythm left/right differences showed bilateral central foci that were stronger on the right side. The independence of mu and beta rhythms was demonstrated by differences for movement and imagery for the subjects as a group and by principal components analysis. The results indicated that the effects of imagery were not simply an attenuated version of the effects of movement. They supply evidence that motor imagery could play an important role in EEG-based communication, and suggest that mu and beta rhythms might provide independent control signals.}, keywords = {beta rhythm, EEG, imagery, mu rhythm, sensorimotor cortex}, issn = {0896-0267}, doi = {10.1023/A:1023437823106}, url = {http://www.ncbi.nlm.nih.gov/pubmed/10791681}, author = {Dennis J. McFarland and Miner, L. A. and Theresa M Vaughan and Jonathan Wolpaw} } @article {3239, title = {What do reflex and voluntary mean? Modern views on an ancient debate.}, journal = {Experimental brain research. Experimentelle Hirnforschung. Exp{\'e}rimentation c{\'e}r{\'e}brale}, volume = {130}, year = {2000}, month = {02/2000}, pages = {417{\textendash}432}, abstract = {Are the words reflex and voluntary useful scientific concepts, or are they prescientific terms that should be discarded? Physiologists use these words routinely in their publications, in laboratory experiments and, indeed, like most lay people, in their daily lives. The tacit assumption is that we all know, more or less, what they mean. However, the issue has a rich history of philosophical and scientific debate; and, as this article demonstrates, present-day researchers still cannot reach a consensus on the meaning of the words and on whether it is possible to draw a scientific distinction between them. The five authors present five quite different analyses. In broad terms, they split into two camps: those who equate voluntary behaviours with consciousness and suppressibility and those who view all behaviours as sensorimotor interactions, the complexity of which determines whether they are reflexive or voluntary. According to the first view, most movements of daily life are neither purely reflex nor purely voluntary. They fall into the middle ground of automatic motor programs. According to the second view, as neuroscience advances the class of reflex behaviours will grow and the class of voluntary behaviours will shrink.}, keywords = {Consciousness, Reflex, voluntary}, issn = {0014-4819}, doi = {10.1007/s002219900250}, url = {http://www.ncbi.nlm.nih.gov/pubmed/10717785}, author = {Prochazka, A. and Clarac, F. and Loeb, G. E. and Rothwell, J. C. and Jonathan Wolpaw} } @article {3240, title = {Operant conditioning of H-reflex increase in spinal cord{\textendash}injured rats.}, journal = {Journal of neurotrauma}, volume = {16}, year = {1999}, month = {02/1999}, pages = {175{\textendash}186}, abstract = {Operant conditioning of the spinal stretch reflex or its electrical analog, the H-reflex, is a new model for exploring the mechanisms of long-term supraspinal control over spinal cord function. Primates and rats can gradually increase (HRup conditioning mode) or decrease (HRdown conditioning mode) the H-reflex when reward is based on H-reflex amplitude. An earlier study indicated that HRdown conditioning of the soleus H-reflex in rats is impaired following contusion injury to thoracic spinal cord. The extent of impairment was correlated with the percent of white matter lost at the injury site. The present study investigated the effects of spinal cord injury on HRup conditioning. Soleus H-reflexes were elicited and recorded with chronically implanted electrodes from 14 rats that had been subjected to calibrated contusion injuries to the spinal cord at T8. At the lesion epicenter, 12-39\% of the white matter remained. After control-mode data were collected, each rat was exposed to the HRup conditioning mode for 50 days. Final H-reflex amplitudes after HRup conditioning averaged 112\% (+/-22\% SD) of control. This value was significantly smaller than that for 13 normal rats exposed to HRup conditioning, in which final amplitude averaged 153\% (+/-51\%) SD of control. As previously reported for HRdown conditioning after spinal cord injury, success was inversely correlated with the severity of the injury as assessed by white matter preservation and by time to return of bladder function. HRup and HRdown conditioning are similarly sensitive to injury. These results further demonstrate that H-reflex conditioning is a sensitive measure of the long-term effects of injury on supraspinal control over spinal cord functions and could prove a valuable measure of therapeutic efficacy.}, keywords = {H-Reflex, operant conditioning, plasticity, rat, soleus muscle, spinal cord injury}, issn = {0897-7151}, url = {http://www.ncbi.nlm.nih.gov/pubmed/10098962}, author = {Xiang Yang Chen and Jonathan Wolpaw and Jakeman, L. B. and Stokes, B. T.} } @article {3164, title = {Sag during unfused tetanic contractions in rat triceps surae motor units.}, journal = {Journal of neurophysiology}, volume = {81}, year = {1999}, month = {06/1999}, pages = {2647{\textendash}2661}, abstract = {Contractile properties and conduction velocity were studied in 202 single motor units of intact rat triceps surae muscles activated by intra-axonal (or intra-myelin) current injection in L5 or L6 ventral root to assess the factors that determine the expression of sag (i.e., decline in force after initial increase during unfused tetanic stimulation). Sag was consistently detected in motor units with unpotentiated twitch contraction times <20 ms. However, the range of frequencies at which sag was expressed varied among motor units such that there was no single interstimulus interval (ISI), with or without adjusting for twitch contraction time, at which sag could be detected reliably. Further analysis indicated that using the absence of sag as a criterion for identifying slow-twitch motor units requires testing with tetani at several different ISIs. In motor units with sag, the shape of the force profile varied with tetanic frequency and contractile properties. Simple sag force profiles (single maximum reached late in the tetanus followed by monotonic decay) tended to occur at shorter ISIs and were observed more frequently in fatigue-resistant motor units with long half-relaxation times and small twitch amplitudes. Complex sag profiles reached an initial maximum early in the tetanus, tended to occur at longer ISIs, and were more common in fatigue-sensitive motor units with long half-relaxation times and large twitch amplitudes. The differences in frequency dependence and force maximum location suggested that these phenomena represented discrete entities. Successive stimuli elicited near-linear increments in force during tetani in motor units that never exhibited sag. In motor units with at least one tetanus displaying sag, tetanic stimulation elicited large initial force increments followed by rapidly decreasing force increments. That the latter force envelope pattern occurred in these units even in tetani without sag suggested that the factors responsible for sag were expressed in the absence of overt sag. The time-to-peak force (TTP) of the individual contractions during a tetanus decreased in tetani with sag. Differences in the pattern of TTP change during a tetanus were consistent with the differences in force maximum location between tetani exhibiting simple and complex sag. Tetani from motor units that never exhibited sag did not display a net decrease in TTP during successive contractions. These data were consistent with the initial force decrement of sag resulting from a transient reduction in the duration of the contractile state.}, keywords = {Regression Analysis}, issn = {0022-3077}, url = {http://www.ncbi.nlm.nih.gov/pubmed/10368385}, author = {Jonathan S. Carp and Herchenroder, P. A. and Xiang Yang Chen and Jonathan Wolpaw} } @article {3243, title = {Answering questions with an electroencephalogram-based brain-computer interface.}, journal = {Archives of physical medicine and rehabilitation}, volume = {79}, year = {1998}, month = {09/1998}, pages = {1029{\textendash}1033}, abstract = {OBJECTIVE: To demonstrate that humans can learn to control selected electroencephalographic components and use that control to answer simple questions. METHODS: Four adults (one with amyotrophic lateral sclerosis) learned to use electroencephalogram (EEG) mu rhythm (8 to 12Hz) or beta rhythm (18 to 25Hz) activity over sensorimotor cortex to control vertical cursor movement to targets at the top or bottom edge of a video screen. In subsequent sessions, the targets were replaced with the words YES and NO, and individuals used the cursor to answer spoken YES/NO questions from single- or multiple-topic question sets. They confirmed their answers through the response verification (RV) procedure, in which the word positions were switched and the question was answered again. RESULTS: For 5 consecutive sessions after initial question training, individuals were asked an average of 4.0 to 4.6 questions per minute; 64\% to 87\% of their answers were confirmed by the RV procedure and 93\% to 99\% of these answers were correct. Performances for single- and multiple-topic question sets did not differ significantly. CONCLUSIONS: The results indicate that (1) EEG-based cursor control can be used to answer simple questions with a high degree of accuracy, (2) attention to auditory queries and formulation of answers does not interfere with EEG-based cursor control, (3) question complexity (at least as represented by single versus multiple-topic question sets) does not noticeably affect performance, and (4) the RV procedure improves accuracy as expected. Several options for increasing the speed of communication appear promising. An EEG-based brain-computer interface could provide a new communication and control modality for people with severe motor disabilities.}, keywords = {User-Computer Interface}, issn = {0003-9993}, doi = {10.1016/S0003-9993(98)90165-4}, url = {http://www.ncbi.nlm.nih.gov/pubmed/9749678}, author = {Miner, L. A. and Dennis J. McFarland and Jonathan Wolpaw} } @article {3241, title = {EEG-based communication: analysis of concurrent EMG activity.}, journal = {Electroencephalography and clinical neurophysiology}, volume = {107}, year = {1998}, month = {12/1998}, pages = {428{\textendash}433}, abstract = {OBJECTIVE: Recent studies indicate that people can learn to control the amplitude of mu or beta rhythms in the EEG recorded from the scalp over sensorimotor cortex and can use that control to move a cursor to targets on the computer screen. While subjects do not move during performance, it is possible that inapparent or unconscious muscle contractions contribute to the changes in the mu and beta rhythm activity responsible for cursor movement. We evaluated this possibility. METHODS: EMG was recorded from 10 distal limb muscle groups while five trained subjects used mu or beta rhythms to move a cursor to targets at the bottom or top edge of a computer screen. RESULTS: EMG activity was very low during performance, averaging 4.0+/-4.4\% (SD) of maximum voluntary contraction. Most important, the correlation, measured as r2, between target position and EMG activity averaged only 0.01+/-0.02, much lower than the correlation between target position and the EEG activity that controlled cursor movement, which averaged 0.39+/-0.18. CONCLUSIONS: These results strongly support the conclusion that EEG-based cursor control does no depend on concurrent muscle activity. EEG-based communication and control might provide a new augmentative communication option for those with severe motor disabilities.}, keywords = {augmentative communication, conditioning, Electroencephalography, Electromyography, mu rhythm, Rehabilitation, sensorimotor cortex}, issn = {0013-4694}, doi = {10.1016/S0013-4694(98)00107-2}, url = {http://www.ncbi.nlm.nih.gov/pubmed/9922089}, author = {Theresa M Vaughan and Miner, L. A. and Dennis J. McFarland and Jonathan Wolpaw} } @article {3244, title = {EEG-based communication and control: short-term role of feedback.}, journal = {IEEE transactions on rehabilitation engineering : a publication of the IEEE Engineering in Medicine and Biology Society}, volume = {6}, year = {1998}, month = {03/1998}, pages = {7{\textendash}11}, abstract = {When people learn to control the amplitudes of certain electroencephalogram (EEG) components (e.g., the 8-12 Hz mu-rhythm over sensorimotor cortex) and use them to move a cursor to a target on a video screen, feedback about performance is normally provided by cursor movement and by trial outcome (i.e., success or failure). We assessed the short-term effects of this feedback on EEG control. After subjects received initial training with feedback present, feedback was removed intermittently for periods of several minutes. Subjects still displayed EEG control when feedback was removed. Removal of cursor movement alone appeared to have effects comparable to removal of both cursor movement and trial outcome. These results show that, in the short-term at least, mu-rhythm control is not dependent on the sensory input provided by cursor movement. They also suggest that feedback can have inhibitory as well as facilitory effects on EEG control, and that these effects vary across subjects. This finding has implications for the design of training procedures.}, keywords = {Sensitivity and Specificity}, issn = {1063-6528}, doi = {10.1109/86.662615}, url = {http://www.ncbi.nlm.nih.gov/pubmed/9535518}, author = {Dennis J. McFarland and McCane, L. M. and Jonathan Wolpaw} } @article {3242, title = {EEG-based communication: improved accuracy by response verification.}, journal = {IEEE transactions on rehabilitation engineering : a publication of the IEEE Engineering in Medicine and Biology Society}, volume = {6}, year = {1998}, month = {09/1998}, pages = {326{\textendash}333}, abstract = {Humans can learn to control the amplitude of electroencephalographic (EEG) activity in specific frequency bands over sensorimotor cortex and use it to move a cursor to a target on a computer screen. EEG-based communication could provide a new augmentative communication channel for individuals with motor disabilities. In the present system, each dimension of cursor movement is controlled by a linear equation. While the intercept in the equation is continually updated, it does not perfectly eliminate the impact of spontaneous variations in EEG amplitude. This imperfection reduces the accuracy of cursor movement. We evaluated a response verification (RV) procedure in which each outcome is determined by two opposite trials (e.g., one top-target trial and one bottom-target trial). Success, or failure, on both is required for a definitive outcome. The RV procedure reduces errors due to imperfection in intercept selection. Accuracy for opposite-trial pairs exceeds that predicted from the accuracies of individual trials, and greatly exceeds that for same-trial pairs. The RV procedure should be particularly valuable when the first trial has >2 possible targets, because the second trial need only confirm or deny the outcome of the first, and it should be applicable to nonlinear as well as to linear algorithms.}, keywords = {Computer-Assisted, Signal Processing}, issn = {1063-6528}, doi = {10.1109/86.712231}, url = {http://www.ncbi.nlm.nih.gov/pubmed/9749910}, author = {Jonathan Wolpaw and Ramoser, H. and Dennis J. McFarland and Pfurtscheller, G.} } @article {3246, title = {The complex structure of a simple memory.}, journal = {Trends in neurosciences}, volume = {20}, year = {1997}, month = {12/1997}, pages = {588{\textendash}594}, abstract = {Operant conditioning of the vertebrate H-reflex, which appears to be closely related to learning that occurs in real life, is accompanied by plasticity at multiple sites. Change occurs in the firing threshold and conduction velocity of the motoneuron, in several different synaptic terminal populations on the motoneuron, and probably in interneurons as well. Change also occurs contralaterally. The corticospinal tract probably has an essential role in producing this plasticity. While certain of these changes, such as that in the firing threshold, are likely to contribute to the rewarded behavior (primary plasticity), others might preserve previously learned behaviors (compensatory plasticity), or are simply activity-driven products of change elsewhere (reactive plasticity). As these data and those from other simple vertebrate and invertebrate models indicate, a complex pattern of plasticity appears to be the necessary and inevitable outcome of even the simplest learning.}, keywords = {H-Reflex, Learning, Memory, operant conditioning, plasticity, Spinal Cord, stretch reflex}, issn = {0166-2236}, doi = {10.1016/S0166-2236(97)01133-8}, url = {http://www.ncbi.nlm.nih.gov/pubmed/9416673}, author = {Jonathan Wolpaw} } @article {3248, title = {Dorsal column but not lateral column transection prevents down-conditioning of H reflex in rats.}, journal = {Journal of neurophysiology}, volume = {78}, year = {1997}, month = {09/1997}, pages = {1730{\textendash}1734}, abstract = {Operant conditioning of the H reflex, the electrical analogue of the spinal stretch reflex, in freely moving rats is a relatively simple model for studying long-term supraspinal control over spinal cord function. Motivated by food reward, rats can gradually increase or decrease the soleus H reflex. This study is the first effort to determine which spinal cord pathways convey the descending influence from supraspinal structures that changes the H reflex. In anesthetized Sprague-Dawley rats, the entire dorsal column (DC), which includes the main corticospinal tract, or the right lateral column (LC) was transected by electrocautery. Animals recovered quickly and the minimal transient effects of transection on the right soleus H reflex disappeared within 16 days. Beginning at least 18 days after transection, 12 rats were exposed to the HRdown-conditioning mode, in which reward was given when the H reflex of the right soleus muscle was below a criterion value. In seven LC rats exposed to the HRdown mode, the H reflex fell to 71 +/- 8\% (mean +/- SE) of its initial value. In six of the seven, conditioning was successful (i.e., decrease to < or = 80\%). These results were comparable with those previously obtained from normal rats. In contrast, in five DC rats exposed to the HRdown mode, the H reflex at the end of exposure was 106 +/- 12\% of its initial value. In none of these rats was HRdown-conditioning successful. DC rats differed significantly from normal and LC rats in both final H reflex values and number successful. In five DC and three LC rats that continued under control conditions over 30-78 days, the H reflex at the end of the period was 98 +/- 4\% and 100 +/- 8\%, respectively, of its initial value, indicating that DC or LC transection itself did not lead to gradual increase or decrease in the H reflex. The results indicate that the DC, containing the main corticospinal tract, is essential for HRdown-conditioning, whereas the ipsilateral LC, containing the main rubrospinal, vestibulospinal, and reticulospinal tracts, is not essential. Combined with the known muscular specificity of conditioning, these results suggest that the main corticospinal tract is essential for HRdown-conditioning. The DC ascending tract might also be necessary. The respective roles of the DC descending and ascending tracts, and transection effects on HRup-conditioning and on the maintenance of both HRup- and HRdown-conditioning after they have occurred, remain to be defined.}, keywords = {Spinal Cord}, issn = {0022-3077}, url = {http://www.ncbi.nlm.nih.gov/pubmed/9310458}, author = {Xiang Yang Chen and Jonathan Wolpaw} } @article {3247, title = {EEG-based communication: evaluation of alternative signal prediction methods.}, journal = {Biomedizinische Technik. Biomedical engineering}, volume = {42}, year = {1997}, month = {09/1997}, pages = {226{\textendash}233}, abstract = {Individuals can learn to control the amplitude of EEG activity in specific frequency bands over sensorimotor cortex and use it to move a cursor to a target on a computer screen. For one-dimensional (i.e., vertical) cursor movement, a linear equation translates the EEG activity into cursor movement. To translate an individual{\textquoteright}s EEG control into cursor control as effectively as possible, the intercept in this equation, which determines whether upward or downward movement occurs, should be set so that top and bottom targets are equally accessible. The present study compares alternative methods for using an individual{\textquoteright}s previous performance to select the intercept for subsequent trials. In offline analyses, five different intercept selection methods were applied to EEG data collected while trained subjects were moving the cursor to targets at the top or bottom edge of the screen. In the first two methods-moving average, and weighted sum-a single intercept was selected for the entire 1-2 sec period of each trial. In the other three methods-blocked moving average, blocked weighted sum, and blocked recursive sum (a variation of the weighted sum)-an intercept was selected for each 200-ms segment of the trial. The results from these methods were compared in regard to their balance between upward and downward movements and their consistency of performance across trials. For all subjects combined, the five methods performed similarly. However, performance across subjects was more consistent for the moving average, blocked moving average, and blocked recursive sum methods than for the weighted sum and blocked weighted sum methods. Due to its consistent performance and its computational simplicity, the moving average method, using the five most recent pairs of top and bottom trials, appears to be the method of choice.}, keywords = {Somatosensory Cortex}, issn = {0013-5585}, doi = {10.1515/bmte.1997.42.9.226}, url = {http://www.ncbi.nlm.nih.gov/pubmed/9342887}, author = {Ramoser, H. and Jonathan Wolpaw and Pfurtscheller, G.} } @article {3249, title = {Spatial filter selection for EEG-based communication.}, journal = {Electroencephalography and clinical neurophysiology}, volume = {103}, year = {1997}, month = {09/1997}, pages = {386{\textendash}394}, abstract = {Individuals can learn to control the amplitude of mu-rhythm activity in the EEG recorded over sensorimotor cortex and use it to move a cursor to a target on a video screen. The speed and accuracy of cursor movement depend on the consistency of the control signal and on the signal-to-noise ratio achieved by the spatial and temporal filtering methods that extract the activity prior to its translation into cursor movement. The present study compared alternative spatial filtering methods. Sixty-four channel EEG data collected while well-trained subjects were moving the cursor to targets at the top or bottom edge of a video screen were analyzed offline by four different spatial filters, namely a standard ear-reference, a common average reference (CAR), a small Laplacian (3 cm to set of surrounding electrodes) and a large Laplacian (6 cm to set of surrounding electrodes). The CAR and large Laplacian methods proved best able to distinguish between top and bottom targets. They were significantly superior to the ear-reference method. The difference in performance between the large Laplacian and small Laplacian methods presumably indicated that the former was better matched to the topographical extent of the EEG control signal. The results as a whole demonstrate the importance of proper spatial filter selection for maximizing the signal-to-noise ratio and thereby improving the speed and accuracy of EEG-based communication.}, keywords = {assistive communication, Electroencephalography, mu rhythm, operant conditioning, prosthesis, Rehabilitation, sensorimotor cortex}, issn = {0013-4694}, doi = {10.1016/S0013-4694(97)00022-2}, url = {http://www.ncbi.nlm.nih.gov/pubmed/9305287}, author = {Dennis J. McFarland and McCane, L. M. and David, S. V. and Jonathan Wolpaw} } @article {3245, title = {Timing of EEG-based cursor control.}, journal = {Journal of clinical neurophysiology : official publication of the American Electroencephalographic Society}, volume = {14}, year = {1997}, month = {11/1997}, pages = {529{\textendash}538}, abstract = {Recent studies show that humans can learn to control the amplitude of electroencephalography (EEG) activity in specific frequency bands over sensorimotor cortex and use it to move a cursor to a target on a computer screen. EEG-based communication could be a valuable new communication and control option for those with severe motor disabilities. Realization of this potential requires detailed knowledge of the characteristic features of EEG control. This study examined the course of EEG control after presentation of a target. At the beginning of each trial, a target appeared at the top or bottom edge of the subject{\textquoteright}s video screen and 1 sec later a cursor began to move vertically as a function of EEG amplitude in a specific frequency band. In well-trained subjects, this amplitude was high at the time the target appeared and then either remained high (i.e., for a top target) or fell rapidly (i.e., for a bottom target). Target-specific EEG amplitude control began 0.5 sec after the target appeared and appeared to wax and wane with a period of approximately 1 sec until the cursor reached the target (i.e., a hit) or the opposite edge of the screen (i.e., a miss). Accuracy was 90\% or greater for each subject. Top-target errors usually occurred later in the trial because of failure to reach and/or maintain sufficiently high amplitude, whereas bottom-target errors usually occurred immediately because of failure to reduce an initially high amplitude quickly enough. The results suggest modifications that could improve performance. These include lengthening the intertrial period, shortening the delay between target appearance and cursor movement, and including time within the trial as a variable in the equation that translates EEG into cursor movement.}, keywords = {assistive communication, Electroencephalography, mu rhythm, operant conditioning, prosthesis, Rehabilitation, sensorimotor cortex}, issn = {0736-0258}, url = {http://www.ncbi.nlm.nih.gov/pubmed/9458060}, author = {Jonathan Wolpaw and Flotzinger, D. and Pfurtscheller, G. and Dennis J. McFarland} } @article {3251, title = {EEG-based communication: prospects and problems.}, journal = {IEEE transactions on rehabilitation engineering : a publication of the IEEE Engineering in Medicine and Biology Society}, volume = {4}, year = {1996}, month = {12/1996}, pages = {425{\textendash}430}, abstract = {Current rehabilitation engineering combines new prosthetic methods with recent developments in personal computers to provide alternative communication and control channels to individuals with motor impairments. Despite these advances, all commercially available systems still require some measure of voluntary motor control. Thus, these systems are not useful for individuals who are totally paralyzed. Electroencephalographic (EEG) activity may provide the basis for a system that would completely bypass normal motor output. EEG-based communication technology might provide assistive devices for individuals who have little or no reliable motor function. This paper reviews the prospects for and problems of EEG-based communication. It summarizes current approaches to development of this new technology, describes the major problems that must be resolved, and focuses on issues critical for its use by those with severe motor disabilities.}, keywords = {Visual Perception}, issn = {1063-6528}, doi = {10.1109/86.547945}, url = {http://www.ncbi.nlm.nih.gov/pubmed/8973969}, author = {Theresa M Vaughan and Jonathan Wolpaw and Emanuel Donchin} } @article {3254, title = {Operant conditioning of H-reflex changes synaptic terminals on primate motoneurons.}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {93}, year = {1996}, month = {08/1996}, pages = {9206{\textendash}9211}, abstract = {Operant conditioning of the primate triceps surae H-reflex, the electrical analog of the spinal stretch reflex, creates a memory trace that includes changes in the spinal cord. To define the morphological correlates of this plasticity, we analyzed the synaptic terminal coverage of triceps surae motoneurons from animals in which the triceps surae H-reflex in one leg had been increased (HRup mode) or decreased (HRdown mode) by conditioning and compared them to each other and to motoneurons from unconditioned animals. Motoneurons were labeled by intramuscular injection of cholera toxin-horseradish peroxidase. A total of 5055 terminals on the cell bodies and proximal dendrites of 114 motoneurons from 14 animals were studied by electron microscopy. Significant differences were found between HRup and HRdown animals and between HRup and naive (i.e., unconditioned) animals. F terminals (i.e., putative inhibitory terminals) were smaller and their active zone coverage on the cell body was lower on motoneurons from the conditioned side of HRup animals than on motoneurons from the conditioned side of HRdown animals. C terminals (i.e., terminals associated with postsynaptic cisterns and rough endoplasmic reticulum) were smaller and the number of C terminals in each C complex (i.e., a group of contiguous C terminals) was larger on motoneurons from the conditioned side of HRup animals than on motoneurons either from the conditioned side of HRdown animals or from naive animals. Because the treatment of HRup and HRdown animals differed only in the reward contingency, the results imply that the two contingencies had different effects on motoneuron synaptic terminals. In combination with other recent data, they show that H-reflex conditioning produces a complex pattern of spinal cord plasticity that includes changes in motoneuron physiological properties as well as in synaptic terminals. Further delineation of this pattern should reveal the contribution of the structural changes described here to the learned change in behavior.}, keywords = {Synapses}, issn = {0027-8424}, url = {http://www.ncbi.nlm.nih.gov/pubmed/8799179}, author = {Feng-Chen, K. C. and Jonathan Wolpaw} } @article {3250, title = {Operant conditioning of H-reflex in spinal cord-injured rats.}, journal = {Journal of neurotrauma}, volume = {13}, year = {1996}, month = {12/1996}, pages = {755{\textendash}766}, abstract = {Operant conditioning of the spinal stretch reflex or its electrical analog, the H-reflex, is a new model for exploring the mechanisms of supraspinal control over spinal cord function. Both rats and primates can gradually increase (HRup conditioning mode) or decrease (HRdown conditioning mode) soleus H-reflex magnitude when exposed to an operant conditioning task. This study used H-reflex operant conditioning to assess and modify spinal cord function after injury. Soleus H-reflexes were elicited and recorded with chronically implanted electrodes from rats that had been subjected to calibrated contusion injuries to the spinal cord at T8. From 18 to 140 days after injury, background EMG, M response amplitude, and initial H-reflex amplitude were not significantly different from those of normal rats. HRdown conditioning was successful in some, but not all, spinal cord-injured rats. The H-reflex decrease achieved by conditioning was inversely correlated with the severity of the injury as assessed histologically or by time to return of bladder function. It was not correlated with the length of time between injury and the beginning of conditioning. The results confirm the importance of descending control from supraspinal structures in mediating operantly conditioned change in H-reflex amplitude. In conjunction with recent human studies, they suggest that H-reflex conditioning could provide a sensitive new means for assessing spinal cord function after injury, and might also provide a method for initiating and guiding functional rehabilitation.}, keywords = {H-Reflex, operant conditioning, plasticity, rat, soleus muscle, spinal cord injury}, issn = {0897-7151}, url = {http://www.ncbi.nlm.nih.gov/pubmed/9002061}, author = {Xiang Yang Chen and Jonathan Wolpaw and Jakeman, L. B. and Stokes, B. T.} } @article {3253, title = {Reversal of H-reflex operant conditioning in the rat.}, journal = {Experimental brain research. Experimentelle Hirnforschung. Exp{\'e}rimentation c{\'e}r{\'e}brale}, volume = {112}, year = {1996}, month = {11/1996}, pages = {58{\textendash}62}, abstract = {In response to an operant conditioning task, rats can gradually increase or decrease soleus H-reflex amplitude without change in background electromyographic activity or M response amplitude. Both increase (under the HRup mode) and decrease (under the HRdown mode) develop over weeks. The present study investigated reversal of conditioned H-reflex change. Following collection of control data, rats were exposed to one mode (HRup or HRdown) for 50 days, and then exposed to the opposite mode for up to 72 days. Rats responded to each mode exposure with gradual, mode-appropriate change in H-reflex amplitude. This finding is consistent with other evidence that H-reflex conditioning depends on spinal cord plasticity. The effects of exposure to the HRup (or HRdown) mode were not affected by whether exposure followed previous exposure to the HRdown (or HRup) mode. In accord with recent studies suggesting that HRup and HRdown conditioning have different spinal mechanisms, these results suggest that reversal of H-reflex change is due primarily to the superimposition of additional plasticity rather than to decay of the plasticity responsible for the initial change.}, keywords = {H-Reflex, operant conditioning, plasticity, rat, soleus muscle, Spinal Cord}, issn = {0014-4819}, doi = {10.1007/BF00227178}, url = {http://www.ncbi.nlm.nih.gov/pubmed/8951407}, author = {Xiang Yang Chen and Jonathan Wolpaw} } @article {3252, title = {Therapeutic neural effects of electrical stimulation.}, journal = {IEEE transactions on rehabilitation engineering : a publication of the IEEE Engineering in Medicine and Biology Society}, volume = {4}, year = {1996}, month = {12/1996}, pages = {218{\textendash}230}, abstract = {The use of a functional neuromuscular stimulation (FNS) device can have therapeutic effects that persist when the device is not in use. Clinicians have reported changes in both voluntary and electrically assisted neuromuscular function and improvements in the condition of soft tissue. Motor recovery has been observed in people with incomplete spinal cord injury, stroke, or traumatic brain injury after the use of motor prostheses. Improvement in voluntary dorsiflexion and overall gait pattern has been reported both in the short term (several hours) and permanently. Electrical stimulation of skin over flexor muscles in the upper limb produced substantial reductions for up to 1 h in the severity of spasticity in brain-injured subjects, as measured by the change in torque generation during ramp-and-hold muscle stretch. There was typically an aggravation of the severity of spasticity when surface stimulation reached intensities sufficient to also excite muscle. Animals were trained to alter the size of the H-reflex to obtain a reward. The plasticity that underlies this operantly conditioned H-reflex change includes changes in the spinal cord itself. Comparable changes appear to occur with acquisition of certain motor skills. Current studies are exploring such changes in humans and animals with spinal cord injuries with the goal of using conditioning methods to assess function after injury and to promote and guide recovery of function. A better understanding of the mechanisms of neural plasticity, achieved through human and animal studies, may help us to design and implement FNS systems that have the potential to produce beneficial changes in the subject{\textquoteright}s central nervous systems.}, keywords = {Treatment Outcome}, issn = {1063-6528}, doi = {10.1109/86.547922}, url = {http://www.ncbi.nlm.nih.gov/pubmed/8973948}, author = {Janis J. Daly and Marsolais, E. B. and Mendell, L. M. and Rymer, W. Z. and Stefanovska, A. and Jonathan Wolpaw and Kantor, C.} } @article {3256, title = {EEG-based brain computer interface (BCI). Search for optimal electrode positions and frequency components.}, journal = {Medical progress through technology}, volume = {21}, year = {1995}, month = {1996}, pages = {111{\textendash}121}, abstract = {Several laboratories around the world have recently started to investigate EEG-based brain computer interface (BCI) systems in order to create a new communication channel for subjects with severe motor impairments. The present paper describes an initial evaluation of 64-channel EEG data recorded while subjects used one EEG channel over the left sensorimotor area to control on-line vertical cursor movement. Targets were given at the top or bottom of a computer screen. Data from 3 subjects in the early stages of training were analyzed by calculating band power time courses and maps for top and bottom targets separately. In addition, the Distinction Sensitive Learning Vector Quantizer (DSLVQ) was applied to single-trial EEG data. It was found that for each subject there exist optimal electrode positions and frequency components for on-line EEG-based cursor control.}, keywords = {User-Computer Interface}, issn = {0047-6552}, url = {http://www.ncbi.nlm.nih.gov/pubmed/8776708}, author = {Pfurtscheller, G. and Flotzinger, D. and Pregenzer, M. and Jonathan Wolpaw and Dennis J. McFarland} } @article {3165, title = {Motoneuron properties after operantly conditioned increase in primate H-reflex.}, journal = {Journal of neurophysiology}, volume = {73}, year = {1995}, month = {04/1995}, pages = {1365{\textendash}1373}, abstract = {1. Monkeys can increase (HRup conditioning mode) or decrease (HRdown conditioning mode) the triceps surae (TS) H-reflex in response to an operant conditioning task. This conditioning modifies the spinal cord. To define this spinal cord plasticity and its role in the behavioral change (H-reflex increase or decrease), we have recorded intracellularly from TS motoneurons in conditioned animals. The present report describes data from HRup animals and compares them with data from previously studied naive (NV; i.e., unconditioned) animals. 2. Thirteen monkeys (Macaca nemestrina, male, 3.8-7.1 kg) were exposed to the HRup conditioning mode, in which reward occurred when H-reflex size in one leg (i.e., the trained leg) was above a criterion value. Conditioning was successful (i.e., increase of > or = 20\%) in 12 of the 13 animals. At the end of conditioning, H-reflex size in the trained leg averaged 188\% of its initial value, whereas size in the control leg averaged 134\% of its initial value. 3. Intracellular recordings were obtained from 136 TS motoneurons on trained (UT + motoneurons) and control (UC + motoneurons) sides of the successful animals. Measurements included axonal conduction velocity, input resistance, time constant, electrotonic length, rheobase, firing threshold to current injection, afterhyperpolarization duration and amplitude, and composite homonymous and heteronymous excitatory postsynaptic potential (EPSP) size and shape. Results were compared with intracellular data from NV animals.(ABSTRACT TRUNCATED AT 250 WORDS)}, keywords = {Reward}, issn = {0022-3077}, url = {http://www.ncbi.nlm.nih.gov/pubmed/7543942}, author = {Jonathan S. Carp and Jonathan Wolpaw} } @article {3257, title = {Operant conditioning of H-reflex in freely moving rats.}, journal = {Journal of neurophysiology}, volume = {73}, year = {1995}, month = {01/1995}, pages = {411{\textendash}415}, abstract = {1. Primates can increase or decrease the spinal stretch reflex and its electrical analogue, the H-reflex (HR), in response to an operant conditioning task. This conditioning changes the spinal cord itself and thereby provides an experimental model for defining the processes and substrates of a learned change in behavior. Because the phenomenon has been demonstrated only in primates, its generality and theoretical implications remain unclear, and its experimental use is restricted by the difficulties of primate research. In response to these issues, the present study explored operant conditioning of the H-reflex in the rat. 2. Seventeen Sprague-Dawley rats implanted with chronic electromyographic (EMG) recording electrodes in one soleus muscle and nerve cuff stimulating electrodes on the posterior tibial nerve were rewarded (either with medial forebrain bundle stimulation or food) for increasing (HRup conditioning mode) or decreasing (HRdown conditioning mode) soleus H-reflex amplitude without change in background EMG or M response (direct muscle response) amplitude. 3. H-reflex amplitude changed appropriately over 3-4 wk. Under the HRup mode, it rose to an average of 158 +/- 54\% (mean +/- SD) of initial value, whereas under the HRdown mode it fell to an average of 67 +/- 11\% of initial value. Background EMG and M response amplitude did not change. 4. Operant conditioning of the H-reflex in the rat appears similar in rate and final magnitude of change to that observed in the monkey.(ABSTRACT TRUNCATED AT 250 WORDS)}, keywords = {Spinal Cord}, issn = {0022-3077}, url = {http://www.ncbi.nlm.nih.gov/pubmed/7714584}, author = {Xiang Yang Chen and Jonathan Wolpaw} } @article {3166, title = {Operantly conditioned motoneuron plasticity: possible role of sodium channels.}, journal = {Journal of neurophysiology}, volume = {73}, year = {1995}, month = {02/1995}, pages = {867{\textendash}871}, abstract = {1. Learning is traditionally thought to depend on synaptic plasticity. However, recent work shows that operantly conditioned decrease in the primate H reflex is associated with an increase in the depolarization needed to fire the spinal motoneuron (VDEP) and a decrease in its conduction velocity (CV). Furthermore, the increase in VDEP appears to be largely responsible for the H-reflex decrease. The conjunction of these changes in VDEP and CV suggests that an alteration in Na+ channel properties throughout the soma and axon could be responsible. 2. A mathematical model of the mammalian myelinated axon was used to test whether a positive shift in the voltage dependence of Na+ channel activation, a decrease in Na+ channel peak permeability, or changes in other fiber properties could have accounted for the experimental findings. 3. A positive shift of 2.2 mV in Na+ channel activation reproduced the experimentally observed changes in VDEP and CV, whereas a reduction in Na+ channel permeability or changes in other fiber properties did not. 4. These results are consistent with the hypothesis that operantly conditioned decrease in the primate H reflex is largely due to a positive shift in the voltage dependence of Na+ channel activation. Recent studies suggest that change in activation of protein kinase C may mediate this effect.}, keywords = {Sodium Channels}, issn = {0022-3077}, url = {http://www.ncbi.nlm.nih.gov/pubmed/7760141}, author = {Halter, J. A. and Jonathan S. Carp and Jonathan Wolpaw} } @article {3255, title = {Operantly conditioned plasticity and circadian rhythm in rat H-reflex are independent phenomena.}, journal = {Neuroscience letters}, volume = {195}, year = {1995}, month = {08/1995}, pages = {109{\textendash}112}, abstract = {Recent studies indicate that rats can increase or decrease H-reflex amplitude in response to an operant conditioning paradigm. In addition, rats also display a circadian rhythm in H-reflex amplitude. As part of the development of H-reflex conditioning in the rat as a new model for defining the plasticity underlying a simple form of learning, this study examined the relationship in the rat between operantly conditioned H-reflex change and the H-reflex circadian rhythm. When H-reflex amplitude increased or decreased in response to the operant conditioning program, its circadian rhythm showed no changes in phase and minimal change in amplitude. Furthermore, animals did not alter daily performance schedule so as to use the rhythm to increase reward probability. Thus, in the rat, H-reflex operant conditioning and the H-reflex circadian rhythm appear to be independent phenomena. The circadian rhythm should not be a significant complicating factor in studies of operantly conditioned H-reflex change.}, keywords = {circadian rhythm, H-Reflex, Learning, Memory, operant conditioning, Rats}, issn = {0304-3940}, doi = {10.1016/0304-3940(95)11793-V}, url = {http://www.ncbi.nlm.nih.gov/pubmed/7478262}, author = {Xiang Yang Chen and Jonathan Wolpaw} } @article {3258, title = {Acquisition and maintenance of the simplest motor skill: investigation of CNS mechanisms.}, journal = {Medicine and science in sports and exercise}, volume = {26}, year = {1994}, month = {12/1994}, pages = {1475{\textendash}1479}, abstract = {The spinal stretch reflex (SSR), or tendon jerk, is the simplest behavior of the vertebrate nervous system. It is mediated primarily by a wholly spinal, two-neuron pathway. Recent studies from several laboratories have shown that primates, human and nonhuman, can gradually increase or decrease the size of the SSR when reward depends on such change. Evidence of this training remains in the spinal cord after all supraspinal influence is removed. Thus, the learning of this simple motor skill changes the spinal cord itself. Comparable spinal plasticity probably plays a role in the acquisition of many complex motor skills. Intracellular physiological and anatomical studies are seeking the location and nature of this spinal cord plasticity. Attention focuses on the most probable sites of change, the group Ia afferent synapse on the alpha motoneuron and the motoneuron itself. Results to date indicate that modifications are present at several places in the spinal cord. Current clinical studies are investigating the use of spinal cord adaptive plasticity as a basis for a new therapeutic approach to spasticity and other forms of abnormal spinal reflex function that result from spinal cord injury, stroke, or other neurological disorders. In the future, understanding of spinal reflex plasticity may lead to development of improved training methods for a variety of motor skills.}, keywords = {conditioning, Learning, Memory, Motor control, plasticity, primate, Spinal Cord, training}, issn = {0195-9131}, url = {http://www.ncbi.nlm.nih.gov/pubmed/7869882}, author = {Jonathan Wolpaw} } @article {3261, title = {Circadian rhythm in rat H-reflex.}, journal = {Brain research}, volume = {648}, year = {1994}, month = {06/1994}, pages = {167{\textendash}170}, abstract = {We measured soleus H-reflex in the Sprague-Dawley rat as a function of time of day. H-reflex amplitude displayed a marked diurnal variation, even though background EMG and M-response amplitude were stable through the day. The H-reflex was largest in the late morning and smallest around midnight. Thus, its rhythm was opposite in phase to the circadian rhythm found in the primate H-reflex. This rhythm is a potentially confounding factor in studies of motor function. Furthermore, its existence implies that the CNS activity underlying a specific motor performance varies with time of day.}, keywords = {circadian rhythm, electromyogram, H-Reflex, rat, soleus}, issn = {0006-8993}, doi = {10.1016/0006-8993(94)91918-6}, url = {http://www.ncbi.nlm.nih.gov/pubmed/7922520}, author = {Xiang Yang Chen and Jonathan Wolpaw} } @article {3260, title = {The influence of stimulus intensity, contralateral masking and handedness on the temporal N1 and the T complex components of the auditory N1 wave, by John F. Connolly.}, journal = {Electroencephalography and clinical neurophysiology}, volume = {91}, year = {1994}, month = {07/1994}, pages = {71{\textendash}76}, keywords = {Humans}, issn = {0013-4694}, doi = {http://dx.doi.org/10.1016/0013-4694(94)90020-5}, url = {http://www.ncbi.nlm.nih.gov/pubmed/7517847}, author = {Jonathan Wolpaw and Anthony T. Cacace} } @article {3167, title = {Motoneuron plasticity underlying operantly conditioned decrease in primate H-reflex.}, journal = {Journal of neurophysiology}, volume = {72}, year = {1994}, month = {07/1994}, pages = {431{\textendash}442}, abstract = {1. Monkeys can gradually increase or decrease the size of the triceps surae H-reflex in response to an operant conditioning task. This conditioning modifies the spinal cord. To determine the location and nature of the spinal cord plasticity and define its role in the behavioral change (i.e., H-reflex increase or decrease) we have recorded intracellularly from triceps surae motoneurons in conditioned animals and compared the results with data from naive (i.e., unconditioned) animals. 2. Eleven monkeys (Macaca nemestrina, male) were exposed to the HRdown conditioning mode, in which reward occurred when H-reflex size in one leg (i.e., the trained leg) was below a criterion value. In six animals (5.1-8.2 kg) H-reflex size in the trained leg fell to 24-58\% of its initial value, whereas in the other five animals (4.0-5.5 kg) it remained at 92-114\% of its initial value. This outcome, which was in accord with recent data indicating that success in HRdown conditioning is age dependent, allowed comparison of intracellular data from successful HRdown animals with data from unsuccessful animals as well as with data from naive (i.e., unconditioned) animals. 3. Intracellular recordings were obtained from 221 triceps surae motoneurons on trained and control sides of successful and unsuccessful HRdown animals. Measurements included axonal conduction velocity, input resistance, time constant, electrotonic length, rheobase, firing threshold, afterhyperpolarization duration and amplitude, and composite homonymous and heteronymous excitatory postsynaptic potentials to peripheral nerve stimulation. Results were compared with data from 109 triceps surae motoneurons in naive animals. 4. Motoneurons from the trained side of successful HRdown animals had a significantly more positive average firing threshold (-52 vs. -55 mV) and a significantly lower average conduction velocity (67 vs. 71 m/s) than those from naive animals. In contrast, motoneurons from the trained side of unsuccessful HRdown animals were not significantly different from naive motoneurons. 5. These data are consistent with the hypothesis that operantly conditioned decrease in H-reflex size is due to a positive shift in motoneuron firing threshold and a consequent increase in the depolarization needed to reach that threshold. 6. The more positive firing threshold, if present in the axon as well as in the soma, could also account for the decreased conduction velocity observed in motoneurons from the trained side of successful animals.}, keywords = {Synaptic Transmission}, issn = {0022-3077}, url = {http://www.ncbi.nlm.nih.gov/pubmed/7965025}, author = {Jonathan S. Carp and Jonathan Wolpaw} } @article {3262, title = {Multichannel EEG-based brain-computer communication.}, journal = {Electroencephalography and clinical neurophysiology}, volume = {90}, year = {1994}, month = {06/1994}, pages = {444{\textendash}449}, abstract = {Individuals who are paralyzed or have other severe movement disorders often need alternative means for communicating with and controlling their environments. In this study, human subjects learned to use two channels of bipolar EEG activity to control 2-dimensional movement of a cursor on a computer screen. Amplitudes of 8-12 Hz activity in the EEG recorded from the scalp across right and left central sulci were determined by fast Fourier transform and combined to control vertical and horizontal cursor movements simultaneously. This independent control of two separate EEG channels cannot be attributed to a non-specific change in brain activity and appeared to be specific to the mu rhythm frequency range. With further development, multichannel EEG-based communication may prove of significant value to those with severe motor disabilities.}, keywords = {assistive communication, Electroencephalography, mu rhythm, operant conditioning, prosthesis, Rehabilitation, sensorimotor cortex}, issn = {0013-4694}, doi = {10.1016/0013-4694(94)90135-X}, url = {http://www.ncbi.nlm.nih.gov/pubmed/7515787}, author = {Jonathan Wolpaw and Dennis J. McFarland} } @article {3264, title = {Operant conditioning of primate H-reflex: phases of development.}, journal = {Neuroscience letters}, volume = {170}, year = {1994}, month = {04/1994}, pages = {203{\textendash}207}, abstract = {This study sought to determine whether operantly conditioned change in the primate triceps surae (TS) H-reflex develops in distinct phases. Data from 20 animals in which the TS H-reflex in one leg was trained up (i.e., HRup mode) and 18 in which it was trained down (i.e., HRdown mode) were averaged to define H-reflex behavior in trained and control legs. In HRup animals, the trained-leg H-reflex showed a large phase I increase in the first two days followed by gradual phase II increase that continued for weeks. The control-leg H-reflex appeared to show much smaller phase I and phase II increases. In HRdown animals, the trained-leg H-reflex decreased gradually over weeks, while the control-leg H-reflex appeared to increase within 2 days and did not change from then on. The initial rapid increase in the HRdown control leg suggested that two early events occurred in the HRdown trained leg: a nonspecific increase like that in the control leg and an operantly conditioned mode-specific decrease. These two effects may have obscured each other, so that H-reflex size in the HRdown trained leg did not drop rapidly in the first few days. These results improve understanding of adaptive H-reflex change as an operantly conditioned phenomenon, and provide encouragement and direction for efforts to reproduce and study the phenomenon in reduced or anesthetized preparations.}, keywords = {Time Factors}, issn = {0304-3940}, url = {http://www.ncbi.nlm.nih.gov/pubmed/8058188}, author = {Jonathan Wolpaw and Maniccia, D. M. and Elia, T.} } @article {3259, title = {Synaptic terminal coverage of primate triceps surae motoneurons.}, journal = {The Journal of comparative neurology}, volume = {345}, year = {1994}, month = {07/1994}, pages = {345{\textendash}358}, abstract = {This study examined the synaptic terminal coverage of primate triceps surae (TS) motoneurons at the electron microscopic level. In three male pigtail macaques, motoneurons were labeled by retrograde transport of cholera toxin-horseradish peroxidase that was injected into TS muscles bilaterally and visualized with tetramethylbenzidine stabilized with diaminobenzidine. Somatic, proximal dendritic, and distal dendritic synaptic terminals were classified by standard criteria and measured. Overall and type-specific synaptic terminal coverages and frequencies were determined. Labeled cells were located in caudal L5 to rostral S1 ventral horn and ranged from 40 to 74 microns in diameter (average, 54 microns). The range and unimodal distribution of diameters, the label used, and the presence of C terminals on almost all cells indicated that the 15 cell bodies and associated proximal dendrites analyzed here probably belonged to alpha-motoneurons. Synaptic terminals covered 39\% of the cell body membrane, 60\% of the proximal dendritic membrane, and 40\% of the distal dendritic membrane. At each of these three sites, F terminals (flattened or pleomorphic vesicles, usually symmetric active zones, average contact length 1.6 microns) were most common, averaging 52\%, 56\%, and 58\% of total coverage and 56\%, 57\%, and 58\% of total number of cell bodies, proximal dendrites, and distal dendrites respectively. S terminals (round vesicles, usually asymmetric active zones, average contact length 1.3 microns) averaged 24\%, 29\%, and 33\% of coverage and 33\%, 35\%, and 36\% of number at these three sites, respectively. Thus, S terminals were slightly more prominent relative to F terminals on distal dendrites than on cell bodies. C terminals (spherical vesicles, subsynaptic cisterns associated with rough endoplasmic reticulum, average contact length 3.5 microns) constituted 24\% and 11\% of total terminal coverage on cell bodies and proximal dendrites, respectively, and averaged 11\% and 6\% of terminal number at these two locations. M terminals (spherical vesicles, postsynaptic Taxi bodies, some with presynaptic terminals, average contact length 2.7 microns) were absent on cell bodies and averaged 3\% and 7\% of total coverage and 2\% and 5\% of terminals on proximal and distal dendrites, respectively. Except for M terminals, which tended to be smaller distally, terminal contact length was not correlated with location. Total and type-specific coverages and frequencies were not correlated with cell body diameter. Primate TS motoneurons are similar to cat TS motoneurons in synaptic terminal morphology, frequency, and distribution. However, primate terminals appear to be smaller, so that the fraction of membrane covered by them is lower.}, keywords = {Spinal Cord}, issn = {0021-9967}, doi = {10.1002/cne.903450303}, url = {http://www.ncbi.nlm.nih.gov/pubmed/7929906}, author = {Starr, K. A. and Jonathan Wolpaw} } @article {3263, title = {Triceps surae motoneuron morphology in the rat: a quantitative light microscopic study.}, journal = {The Journal of comparative neurology}, volume = {343}, year = {1994}, month = {05/1994}, pages = {143{\textendash}157}, abstract = {The rat is now the model of choice for many studies of motor function. However, little quantitative information on the structure of rat motoneurons is available. In conjunction with efforts to define the physiologic and anatomic substrates of operantly conditioned plasticity in the spinal cord, 13 physiologically identified triceps surae motoneurons in the rat lumbar spinal cord were labeled intracellularly with horseradish peroxidase and completely reconstructed and measured with a computer-based neuron-tracing system. Somata were all located in the ventral horn of lumbar segments 4-5, had an average diameter of 35 microns, and had 6-12 dendrites. Dendrites ramified throughout the ventral horn and also penetrated the white matter. Their spread was greater in the rostrocaudal and dorsoventral directions (1.53 +/- 0.24 mm and 1.35 +/- 0.23 mm, respectively) than in the mediolateral direction (0.85 +/- 0.14 mm). Regardless of soma location, dendritic fields usually extended throughout the ipsilateral coronal cross-section of the ventral horn. As a result, the ventral or lateral extent of the field was correlated strongly with the soma{\textquoteright}s distance from the ventral or lateral border, respectively, of the ventral horn. Furthermore, although soma locations in the coronal plane varied widely, the centers of the dendritic fields tended to cluster near the center of the ventral horn. Dendrites constituted 96.2-98.4\% (mean +/- SD = 97.3 +/- 0.7\%) of the total neuronal surface area. Each of the 104 dendrites studied had an average of 13 branch points and 27 segments. First-order segment diameters ranged from 1.4 to 11.7 microns (mean +/- SD = 5.3 +/- 2.1 microns). Total dendritic length, surface area, volume, number of dendritic segments, and maximum segment order were correlated strongly with diameter of the first-order segment. Proceeding distally between branch points, the mean decrease in dendritic diameter (i.e., tapering) +/- the standard deviation was 22 +/- 8\% of the proximal diameter. The average ratio +/- the standard deviation of the sum of the average diameters of each daughter segment raised to the 1.5 power to the average diameter of the parent segment raised to the 1.5 power (i.e., Rall{\textquoteright}s ratio; Rall, 1959) was 0.87 +/- 0.08. In comparison with cat alpha-motoneurons, rat motoneurons had smaller soma diameters, fewer dendrites, smaller total surface areas, and shorter total dendritic lengths. However, the number of terminations per dendrite was similar in the two species, so that rat motoneurons had more terminations per unit dendritic length.(ABSTRACT TRUNCATED AT 400 WORDS)}, keywords = {computer assisted, dendrites, horseradish peroxidase, image processing, Software, Spinal Cord}, issn = {0021-9967}, doi = {10.1002/cne.903430111}, url = {http://www.ncbi.nlm.nih.gov/pubmed/8027432}, author = {Xiang Yang Chen and Jonathan Wolpaw} } @article {3170, title = {Adaptive plasticity in spinal cord.}, journal = {Advances in neurology}, volume = {59}, year = {1993}, month = {1993}, pages = {163{\textendash}174}, keywords = {Spinal Cord}, issn = {0091-3952}, url = {http://www.ncbi.nlm.nih.gov/pubmed/8420103}, author = {Jonathan Wolpaw and Jonathan S. Carp} } @article {3265, title = {Ethical and social issues in organ procurement for transplantation.}, journal = {New York state journal of medicine}, volume = {93}, year = {1993}, month = {01/1993}, pages = {30{\textendash}34}, keywords = {Voluntary Programs}, issn = {0028-7628}, url = {http://www.ncbi.nlm.nih.gov/pubmed/8429950}, author = {Rosner, F. and Henry, J. B. and Jonathan Wolpaw and Sordillo, P. P. and Sechzer, P. H. and Rogatz, P. and Risemberg, H. M. and Ona, F. V. and Numann, P. J. and Lowenstein, R. E.} } @article {3172, title = {Operant conditioning of the primate H-reflex: factors affecting the magnitude of change.}, journal = {Experimental brain research. Experimentelle Hirnforschung. Exp{\'e}rimentation c{\'e}r{\'e}brale}, volume = {97}, year = {1993}, month = {12/1993}, pages = {31{\textendash}39}, abstract = {Primates can gradually increase or decrease H-reflex amplitude in one leg when reward depends on that amplitude. The magnitude of change varies greatly from animal to animal. This study sought to define the factors that control this magnitude. It evaluated the influence of animal age, muscle size (absolute and relative), background electromyographic activity (EMG) level, M response amplitude, initial H-reflex amplitude, performance intensity, and behavior of the contralateral leg. Fifty-four animals (Macaca nemestrina) underwent operant conditioning of the triceps surae H-reflex in one leg (the trained leg). Twenty-eight were rewarded for larger H-reflexes (HRup animals), and 26 were rewarded for smaller H-reflexes (HRdown animals). In the HRup animals, H-reflex amplitude in the trained leg rose to an average final value of 177\% of its initial amplitude. Magnitude of increase varied widely across animals. Nine animals rose to 120-140\%, 11 to 160-240\%, three to 300\% or more, and five remained within 20\% of initial amplitude. In the HRdown animals, H-reflex amplitude in the trained leg decreased to an average of 69\% of initial amplitude. Magnitude of decrease varied widely. Five animals decreased to 20-40\%, seven to 40-60\%, six to 60-80\%, and eight remained within 20\% of initial amplitude. Animal age, as assessed by weight, markedly affected HRdown conditioning, but not HRup conditioning. Heavy HRdown animals (> or = 6 kg) were more successful than light HRdown animals (< 6 kg). Thirteen of 14 heavy animals and only five of 12 light animals decreased to less than 80\% of initial amplitude.(ABSTRACT TRUNCATED AT 250 WORDS)}, keywords = {H-Reflex, monkey, operant conditioning, plasticity, Spinal Cord}, issn = {0014-4819}, doi = {10.1007/BF00228815}, url = {http://www.ncbi.nlm.nih.gov/pubmed/8131830}, author = {Jonathan Wolpaw and Herchenroder, P. A. and Jonathan S. Carp} } @article {3171, title = {The volitional nature of the simplest reflex.}, journal = {Acta neurobiologiae experimentalis}, volume = {53}, year = {1993}, pages = {103{\textendash}111}, abstract = {Recent studies suggest that none of the behaviors of the vertebrate CNS are fixed responses incapable of change. Even the simplest reflex of all, the two-neuron, monosynaptic spinal stretch reflex (SSR), undergoes adaptive change under appropriate circumstances. Operantly conditioned SSR change occurs gradually over days and weeks and is associated with a complex pattern of CNS plasticity at both spinal and supraspinal sites.}, keywords = {behavior, Brain, conditioning, human physiology, Learning, Memory, motoneuron, nature, primate, Reflex, Spinal Cord, spinal site, supra spinal site, vertebrate}, issn = {0065-1400}, url = {http://www.ncbi.nlm.nih.gov/pubmed/8317238}, author = {Jonathan Wolpaw and Jonathan S. Carp} } @article {3174, title = {Constancy of motor axon conduction time during growth in rats.}, journal = {Experimental brain research. Experimentelle Hirnforschung. Exp{\'e}rimentation c{\'e}r{\'e}brale}, volume = {90}, year = {1992}, month = {08/1992}, pages = {343{\textendash}345}, abstract = {Axon conduction distance, conduction velocity, and conduction time were measured for individual triceps surae motoneurons in Sprague-Dawley rats weighing 230-630 g (i.e., age range 6-16 weeks). Both conduction distance (nerve length) and velocity were closely correlated with weight (r = 0.95 and r = 0.82, respectively). In contrast, conduction time did not change as weight increased nearly threefold. This striking constancy is probably due to a corresponding increase in axon diameter. It could contribute to maintenance of stable motor performance during rapid growth.}, keywords = {development, motoneuron, motor axon, nerve conduction, rat}, issn = {0014-4819}, doi = {10.1007/BF00227247}, url = {http://www.ncbi.nlm.nih.gov/pubmed/1397148}, author = {Xiang Yang Chen and Jonathan S. Carp and Jonathan Wolpaw} } @article {3266, title = {Ethical considerations concerning the HIV-positive physician.}, journal = {New York state journal of medicine}, volume = {92}, year = {1992}, month = {04/1992}, pages = {151{\textendash}155}, keywords = {Voluntary Programs}, issn = {0028-7628}, url = {http://www.ncbi.nlm.nih.gov/pubmed/1594147}, author = {Rosner, F. and Sordillo, P. P. and Jonathan Wolpaw and Farnsworth, P. B. and Bennett, A. J. and Buscaglia, A. and Cassell, E. J. and Halpern, A. L. and Henry, J. B. and Kark, P. R.} } @article {3267, title = {An EEG-based brain-computer interface for cursor control.}, journal = {Electroencephalography and clinical neurophysiology}, volume = {78}, year = {1991}, month = {03/1991}, pages = {252{\textendash}259}, abstract = {This study began development of a new communication and control modality for individuals with severe motor deficits. We trained normal subjects to use the 8-12 Hz mu rhythm recorded from the scalp over the central sulcus of one hemisphere to move a cursor from the center of a video screen to a target located at the top or bottom edge. Mu rhythm amplitude was assessed by on-line frequency analysis and translated into cursor movement: larger amplitudes moved the cursor up and smaller amplitudes moved it down. Over several weeks, subjects learned to change mu rhythm amplitude quickly and accurately, so that the cursor typically reached the target in 3 sec. The parameters that translated mu rhythm amplitudes into cursor movements were derived from evaluation of the distributions of amplitudes in response to top and bottom targets. The use of these distributions was a distinctive feature of this study and the key factor in its success. Refinements in training procedures and in the distribution-based method used to translate mu rhythm amplitudes into cursor movements should further improve this 1-dimensional control. Achievement of 2-dimensional control is under study. The mu rhythm may provide a significant new communication and control option for disabled individuals.}, keywords = {Communication, computer control, EEG, mu rhythm, operant conditioning, prosthesis, sensorimotor rhythm}, issn = {0013-4694}, doi = {10.1016/0013-4694(91)90040-B}, url = {http://www.ncbi.nlm.nih.gov/pubmed/1707798}, author = {Jonathan Wolpaw and Dennis J. McFarland and Neat, G. W. and Forneris, C. A.} } @article {3176, title = {Operantly conditioned plasticity in spinal cord.}, journal = {Annals of the New York Academy of Sciences}, volume = {627}, year = {1991}, month = {08/1991}, pages = {338{\textendash}348}, abstract = {Recent work has shown that the monosynaptic pathway of the SSR can be operantly conditioned, and that a significant part of the plasticity responsible for the behavioral change resides in the spinal cord. The most likely sites of this activity-driven plasticity are the synapse of the Ia afferent neuron on the motoneuron and/or the motoneuron itself. Because the SSR pathway is the simplest and most accessible stimulus-response pathway in the vertebrate CNS, it may provide a valuable experimental model for elucidating activity-driven CNS changes responsible for learning.}, keywords = {Spinal Cord}, issn = {0077-8923}, doi = {10.1111/j.1749-6632.1991.tb25936.x}, url = {http://www.ncbi.nlm.nih.gov/pubmed/1883143}, author = {Jonathan Wolpaw and Lee, C. L. and Jonathan S. Carp} } @article {3268, title = {The allocation of scarce medical resources.}, journal = {New York state journal of medicine}, volume = {90}, year = {1990}, month = {11/1990}, pages = {552{\textendash}558}, keywords = {Vulnerable Populations}, issn = {0028-7628}, url = {http://www.ncbi.nlm.nih.gov/pubmed/2287500}, author = {Rosner, F. and Sordillo, P. P. and Sechzer, P. H. and Risemberg, H. M. and Ona, F. V. and Numann, P. J. and Loeb, L. and Farnsworth, P. B. and Bennett, A. J. and Jonathan Wolpaw} } @article {3270, title = {Human middle-latency auditory evoked potentials: vertex and temporal components.}, journal = {Electroencephalography and clinical neurophysiology}, volume = {77}, year = {1990}, month = {02/1990}, pages = {6{\textendash}18}, abstract = {We recorded middle-latency (20-70 msec) auditory evoked potentials (MLAEPs) to monaural and binaural clicks in 30 normal adults (ages 20-49 years) at 32 scalp locations all referred to a balanced non-cephalic reference. Our goal was to define the MLAEP components that were present at comparable latencies and comparable locations across the subject population. Group and individual data were evaluated both as topographic maps and as MLAEPs at selected electrode locations. Three major components occurred between 20 and 70 msec, two well-known peaks centered at the vertex, and one previously undefined peak focused over the posterior temporal area. Pa is a 29 msec positive peak centered at the vertex and present with both monaural and binaural stimulation. Pb is a 53 msec positive peak also centered at the vertex but seen consistently only with binaural and right ear stimulation. TP41 is a 41 msec positive peak focused over both temporal areas. TP41 has not been identified in previous MLAEP studies that concentrated on central scalp locations and/or used active reference electrode sites such as ears or mastoids. Available topographic, intracranial, pharmacologic, and lesion studies indicate that Pa, Pb and TP41 are of neural origin. Whether Pa and/or Pb are produced in Heschl{\textquoteright}s gyrus, primary auditory cortex, remains unclear. TP41 is probably produced by auditory cortex on the posterior lateral surface of the temporal lobe. It should prove of considerable value in experimental and clinical evaluation of higher level auditory function in particular and of cortical function in general.}, keywords = {(human), middle-latency auditory evoked potential (MLAEP), temporal components, vertex components}, issn = {0013-4694}, doi = {10.1016/0168-5597(90)90012-3}, url = {http://www.ncbi.nlm.nih.gov/pubmed/1688786}, author = {Anthony T. Cacace and Satya-Murti, S. and Jonathan Wolpaw} } @article {3177, title = {Memory traces in spinal cord.}, journal = {Trends in neurosciences}, volume = {13}, year = {1990}, month = {04/1990}, pages = {137{\textendash}142}, abstract = {The complexity and inaccessibility of the vertebrate CNS impede the localization and description of memory traces and the definition of the processes that create them. Recent work has shown that the spinal stretch reflex (SSR), which is produced by a monosynaptic two-neuron pathway, can be operantly conditioned, and that memory traces responsible for this behavioral change reside in the spinal cord. The probable locations are the terminal of the Ia affernt neuron on the motoneuron and/or the motoneuron itself. Because it modifies a simple well-defined and accessible pathway, SSR conditioning may be a valuable experimental model for studying vertebrate memory.}, keywords = {Spinal Cord}, issn = {0166-2236}, doi = {10.1016/0166-2236(90)90005-U}, url = {http://www.ncbi.nlm.nih.gov/pubmed/1692170}, author = {Jonathan Wolpaw and Jonathan S. Carp} } @article {3269, title = {Operant conditioning of H-reflex in freely moving monkeys.}, journal = {Journal of neuroscience methods}, volume = {31}, year = {1990}, month = {02/1990}, pages = {145{\textendash}152}, abstract = {The H-reflex, the electrical analog of the stretch reflex or tendon jerk, is the simplest behavior of the primate CNS. It is subserved by a wholly spinal two-neuron reflex arc. Recent studies show that this reflex can be increased or decreased by operant conditioning, and that such conditioning causes plastic changes in the spinal cord itself. Thus, H-reflex conditioning provides a powerful new model for investigating primate memory traces. The key feature of this model, the conditioning task, originally required animal restraint. This report describes a new tether-based design that allows H-reflex measurement and conditioning without restraint. This design integrates the conditioning task into the life of the freely moving animal.}, keywords = {conditioning, H-Reflex, Memory, plasticity, primate, spinal reflex, stretch reflex}, issn = {0165-0270}, doi = {10.1016/0165-0270(90)90159-D}, url = {http://www.ncbi.nlm.nih.gov/pubmed/2319815}, author = {Jonathan Wolpaw and Herchenroder, P. A.} } @article {3272, title = {Chronic exposure of primates to 60-Hz electric and magnetic fields: III. Neurophysiologic effects.}, journal = {Bioelectromagnetics}, volume = {10}, year = {1989}, month = {01/1989}, pages = {303{\textendash}317}, abstract = {The neurophysiologic effects of combined 60-Hz electric (E) and magnetic (B) fields, of magnitudes comparable to those produced by high-voltage powerlines, were investigated in 10 monkeys (Macaca nemestrina). Six animals (experimental group) were each exposed to three different levels of E and B fields: 3 kV/m and 0.1 G, 10 kV/m and 0.3 G, and 30 kV/m and 0.9 G. Field exposures were preceded and followed by sham exposures, during which factors of field generation were present (e.g., heat, vibration, noise, etc.) without E and B fields. Each of the five segments (i.e., the three exposure segments and the initial and final sham exposure segments) lasted 3 weeks. Animals were exposed for 18 h/day (fields on at 1600 h, off at 1000 h). Four other animals (external control group) were given sham exposure for the entire 15-week period. Auditory, visual, and somatosensory evoked potentials were recorded twice a week, during the daily 6-h field-off period. E- and B-field exposure had no effect on the early or mid-latency evoked potential components, suggesting that exposure at these levels has no effect on peripheral or central sensory afferent pathways. However, there was a statistically significant decrease in the amplitudes of late components of the somatosensory evoked potential during the 10kV/m and 0.3 G, and 30 kV/m and 0.9 G exposure levels. This result is possibly related to the opiate antagonist effect of electromagnetic field exposure reported by others.}, keywords = {60-Hz electromagnetic radiation, auditory, brainstem auditory, evoked potential, primates, somatosensory, visual}, issn = {0197-8462}, doi = {10.1002/bem.2250100308}, url = {http://www.ncbi.nlm.nih.gov/pubmed/2751703}, author = {Dowman, R. and Jonathan Wolpaw and Seegal, R. F. and Satya-Murti, S.} } @article {3273, title = {Chronic exposure of primates to 60-Hz electric and magnetic fields: I. Exposure system and measurements of general health and performance.}, journal = {Bioelectromagnetics}, volume = {10}, year = {1989}, month = {01/1989}, pages = {277{\textendash}288}, abstract = {We exposed pigtailed macaques (Macaca nemestrina) to electric (E) and magnetic (B) fields at strengths of 3 kV/m and 0.1 G, 10 kV/m and 0.3 G, and 30 kV/m and 0.9 G for three 21 day segments. These three exposure segments were preceded and followed by 21 day sham exposure segments. Additional animals received only sham exposure for five 21 day segments. Detailed description of the exposure chamber and field generation apparatus is given. We evaluated measures of animal well-being, including weight, blood chemistry, blood cell counts, and performance on a simple motor task, and performed postmortem examinations. Reliable and consistent results were obtained throughout data collection. None of the measures evaluated was significantly affected by E- and B-field exposures. Data obtained during actual exposure segments were not distinguishable from those obtained during the initial and final sham exposure segments, nor were they different from data obtained from the sham-exposed animals. Thus, field exposure had no apparent effects on general health or performance.}, keywords = {60-Hz fields, central nervous system, electric field, magnetic field, primate}, issn = {0197-8462}, doi = {10.1002/bem.2250100306}, url = {http://www.ncbi.nlm.nih.gov/pubmed/2751702}, author = {Jonathan Wolpaw and Seegal, R. F. and Dowman, R.} } @article {3275, title = {Chronic exposure of primates to 60-Hz electric and magnetic fields: II. Neurochemical effects.}, journal = {Bioelectromagnetics}, volume = {10}, year = {1989}, month = {01/1989}, pages = {289{\textendash}301}, abstract = {We exposed Macaca nemestrina (pig-tailed macaques) to electric (E) and magnetic (B) fields ranging in intensity from 3 kV/m and 0.1 G to 30 kV/m and 0.9 G for three 21-day (d) periods. Experimental animals were exposed to sham E and B fields for two 21-d periods, one prior to and one following actual exposure to E and B fields, resulting in a total of five 21-d periods. Control animals were exposed to sham E and B fields for the entire 105-d interval. At the end of each 21-d period cerebrospinal fluid (CSF) was obtained by lumbar puncture and analyzed for concentrations of homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA), metabolites of dopamine and serotonin neurotransmitters, respectively, by high-performance liquid chromatography with electrochemical detection (HPLC-ECD). Results are based on an examination of six experimental and four control animals. Exposure to E and B fields at all strengths was associated with a significant decline in CSF concentrations of both HVA and 5-HIAA when statistical comparisons were made against values obtained at the end of the preexposure interval. However, HVA returned to preexposure levels during the postexposure period, while 5-HIAA did not. No significant change in the concentrations of HVA or 5-HIAA was noted in the control animals. These results strongly suggest that exposure of the nonhuman primate to E and B fields can significantly affect specific biochemical estimates of nervous system function. These effects may involve alterations either in neuronal activity or in the activity of enzymes that catabolize the neurotransmitters.}, keywords = {Neurotransmitter Agents}, issn = {0197-8462}, doi = {10.1002/bem.2250100307}, url = {http://www.ncbi.nlm.nih.gov/pubmed/2473755}, author = {Seegal, R. F. and Jonathan Wolpaw and Dowman, R.} } @article {3276, title = {Diurnal rhythms in primate spinal reflexes and accompanying cortical somatosensory evoked potentials.}, journal = {Electroencephalography and clinical neurophysiology}, volume = {72}, year = {1989}, month = {01/1989}, pages = {69{\textendash}80}, abstract = {We recorded spinal reflexes and cortical somatosensory evoked potentials (SEPs), elicited by stretching the biceps or the triceps muscle or by electrically stimulating the posterior tibial nerve, from monkeys throughout the day. Amplitudes of the spinal stretch reflex (SSR) and of its electrically evoked analogue, the H-reflex, varied diurnally: both were greatest midway through the lights-off period and smallest during the lights-on period. Stretch-evoked and electrically evoked SEP amplitudes also varied diurnally, but were out of phase with the spinal reflex rhythms. The H-reflex is elicited by direct stimulation of the nerve and thus, unlike the SSR, bypasses the muscle spindle. The H-reflex diurnal rhythm and the phase difference between the spinal reflex and SEP diurnal rhythms indicate that these rhythms are mediated at least in part by central mechanisms. Furthermore, both the spinal reflex and SEP diurnal rhythms appeared to be entrained by the light-dark cycle, which suggests that they may be coupled to the same oscillator. Besides their theoretical importance, these rhythms have important implications for experimental and clinical studies of spinal reflexes and SEPs. These rhythms are especially pertinent to the interpretation of long-term monitoring studies, as are often carried out in the Intensive Care Unit and during lengthy neurosurgical procedures.}, keywords = {Spinal Cord}, issn = {0013-4694}, doi = {10.1016/0013-4694(89)90032-1}, url = {http://www.ncbi.nlm.nih.gov/pubmed/2464477}, author = {Dowman, R. and Jonathan Wolpaw} } @article {3271, title = {Memory traces in primate spinal cord produced by operant conditioning of H-reflex.}, journal = {Journal of neurophysiology}, volume = {61}, year = {1989}, month = {03/1989}, pages = {563{\textendash}572}, abstract = {1. Study of memory traces in higher animals requires experimental models possessing well-localized and technically accessible memory traces{\textendash}plasticity responsible for behavioral change, not dependent on control from elsewhere, and open to detailed investigation. Our purpose has been to develop such a model based on the wholly spinal, largely monosynaptic path of the spinal stretch reflex. Previous studies described operant conditioning of this reflex and of its electrical analog, the H-reflex. In this study, we sought to determine whether conditioning causes changes in the spinal cord that affect the reflex and are not dependent on continued supraspinal influence, and thus qualify as memory traces. 2. Sixteen monkeys underwent chronic conditioning of the triceps surae H-reflex. Eight were rewarded for increasing H-reflex amplitude (HR increases mode), and eight were rewarded for decreasing it (HR decreases mode). In each animal, the other leg was an internal control. Over several months of conditioning, H-reflex amplitude in the conditioned leg rose in HR increases animals and fell in HR decreases animals. H-reflex amplitude in the control leg changed little. 3. After HR increases or HR decreases conditioning, each animal was deeply anesthetized and surgically prepared. The reflex response to supramaximal dorsal root stimulation was measured from the triceps surae nerve as percent of response to supramaximal ventral root stimulation, which was the maximum possible response. Data from both legs were collected before and for up to 3 days after thoracic (T9-10) cord transection. The animal remained deeply anesthetized throughout and was killed by overdose. 4. The reflex asymmetries produced by conditioning were still present several days after transection removed supraspinal influence: reflexes of HR increases animals were significantly larger in HR increases legs than in control legs and reflexes of HR decreases animals were significantly smaller in HR decreases legs than in control legs. 5. Reflex amplitude was much greater in the control legs of anesthetized HR decreases animals than in the control legs of anesthetized HR increases animals. 6. Chronic conditioning had at least two effects on the spinal cord. The first effect, task-appropriate reflex asymmetry, was evident both in the awake behaving animal and in the anesthetized transected animal. The second effect, larger control leg reflexes in HR decreases than in HR increases animals, was evident only in the anesthetized animal. By removing supraspinal control, anesthesia and transection revealed a previously hidden effect of conditioning.(ABSTRACT TRUNCATED AT 400 WORDS)}, keywords = {Spinal Cord}, issn = {0022-3077}, url = {http://www.ncbi.nlm.nih.gov/pubmed/2709100}, author = {Jonathan Wolpaw and Lee, C. L.} } @article {3178, title = {Memory traces in spinal cord produced by H-reflex conditioning: effects of post-tetanic potentiation.}, journal = {Neuroscience letters}, volume = {103}, year = {1989}, month = {08/1989}, pages = {113{\textendash}119}, abstract = {Operant conditioning of the wholly spinal, largely monosynaptic triceps surae H-reflex in monkeys causes changes in lumbosacral spinal cord that persist after removal of supraspinal influence. We evaluated the interaction between post-tetanic potentiation and these memory traces. Animals in which the triceps surae H-reflex in one leg had been increased or decreased by conditioning were deeply anesthetized, and monosynaptic reflexes to L6-S1 dorsal root stimulation were recorded before and after tetanization from both legs for 3 days after thoracic cord transection. Animals remained anesthetized throughout and were sacrificed by overdose. Reflex asymmetries consistent with the effect of H-reflex conditioning were present after transection and persisted through the 3 days of study. Tetanization affected conditioned leg and control leg reflexes similarly. This finding suggests that, while post-tetanic potentiation and probably H-reflex conditioning alter Ia synaptic transmission, the two phenomena have different mechanisms.}, keywords = {conditioning, Learning, Memory, motoneuron, potentiation, primate, spinal reflex}, issn = {0304-3940}, doi = {10.1016/0304-3940(89)90495-3}, url = {http://www.ncbi.nlm.nih.gov/pubmed/2779852}, author = {Jonathan Wolpaw and Jonathan S. Carp and Lee, C. L.} } @article {3274, title = {Operant conditioning of primate triceps surae H-reflex produces reflex asymmetry.}, journal = {Experimental brain research. Experimentelle Hirnforschung. Exp{\'e}rimentation c{\'e}r{\'e}brale}, volume = {75}, year = {1989}, month = {03/1989}, pages = {35{\textendash}39}, abstract = {Monkeys are able to increase or decrease triceps surae H-reflex when reward depends on reflex amplitude. Operantly conditioned change occurs over weeks and produces persistent alterations in the lumbosacral spinal cord which should be technically accessible substrates of primate memory. Previous work monitored and conditioned triceps surae H-reflex in one leg. To determine whether H-reflex conditioning in one leg affects the control leg, the present study monitored H-reflexes in both legs while the reflex in one leg underwent HR increases or HR decreases conditioning. Under the HR increases mode, H-reflex increase was much greater in the HR increases leg than in the control leg. Under the HR decreases mode, H-reflex decrease was confined to the HR decreases leg. By showing that conditioning of one leg{\textquoteright}s H-reflex produces H-reflex asymmetry, the data further define the phenomenon and indicate that the other leg can serve as an internal control for physiologic and anatomic studies exploring the sites and mechanisms of the spinal cord memory substrates.}, keywords = {Learning, Memory, monosynaptic reflex, operant conditioning, plasticity, Spinal Cord, spinal reflex}, issn = {0014-4819}, doi = {10.1007/BF00248527}, url = {http://www.ncbi.nlm.nih.gov/pubmed/2707354}, author = {Jonathan Wolpaw and Lee, C. L. and Calaitges, J. G.} } @article {3277, title = {Jendrassik maneuver facilitates soleus H-reflex without change in average soleus motoneuron pool membrane potential.}, journal = {Experimental neurology}, volume = {101}, year = {1988}, month = {08/1988}, pages = {288{\textendash}302}, abstract = {Facilitation of spinal reflex amplitude by remote muscle contraction, otherwise known as the Jendrassik maneuver (JM), was first shown over 100 years ago, yet the mechanism by which this facilitation operates remains undetermined. Earlier work has eliminated participation of the muscle spindle in JM-induced spinal reflex facilitation, leaving changes in postsynaptic (e.g., change in average soleus motoneuron membrane potential) and presynaptic (e.g., inhibition of presynaptic inhibition) mechanisms as viable candidates. We recorded background EMG in the soleus muscle during JM-induced soleus H-reflex facilitation in humans. The JM in this experiment consisted of wrist muscle contraction. Soleus background EMG was maintained by the subject at either a zero level (e.g., relaxed) or a specified moderate level prior to and during the JM. The JM increased H-reflex amplitude by comparable amounts in both situations, but had no effect on soleus background EMG. Given the well-known relationship between the average motoneuron pool membrane potential and background EMG, we conclude that JM facilitation of the soleus H-reflex is not caused by an increase in background excitatory input to the soleus motoneuron pool. Remaining candidates for mediation of JM induced H-reflex facilitation include change in stimulus-evoked afferent input at some point proximal to the muscle spindle, such as reduction in presynaptic inhibition, or a change in motoneuron input resistance.}, keywords = {Reflex, Stretch}, issn = {0014-4886}, doi = {10.1016/0014-4886(88)90012-X}, url = {http://www.ncbi.nlm.nih.gov/pubmed/3396646}, author = {Dowman, R. and Jonathan Wolpaw} } @article {3279, title = {Operant conditioning of primate spinal reflexes: effect on cortical SEPs.}, journal = {Electroencephalography and clinical neurophysiology}, volume = {69}, year = {1988}, month = {04/1988}, pages = {398{\textendash}401}, abstract = {Previous studies have demonstrated operant conditioning of the primate spinal stretch reflex (SSR) and of its electrical analog, the H-reflex. We studied the evoked potential recorded over primary somatosensory cortex (SEP) which accompanies the H-reflex to determine whether the initial cortical response changes in the course of conditioned H-reflex change. When H-reflex amplitude changed, SEP amplitude also changed, but only half as much as the H-reflex. The results indicate that, while operant conditioning of the H-reflex has its largest effect on the spinal pathway of the reflex, it also has some effect on supraspinal pathways of the initial cortical response.}, keywords = {cortical response, H-Reflex, Learning, Memory, operant conditioning, plasticity, somatosensory evoked potential, spinal reflex}, issn = {0013-4694}, doi = {10.1016/0013-4694(88)90012-0}, url = {http://www.ncbi.nlm.nih.gov/pubmed/2450739}, author = {Jonathan Wolpaw and Dowman, R.} } @article {3281, title = {Retrograde transport of the lectin Phaseolus vulgaris leucoagglutinin (PHA-L) by rat spinal motoneurons.}, journal = {Neuroscience letters}, volume = {86}, year = {1988}, month = {03/1988}, pages = {133{\textendash}138}, abstract = {The lectin Phaseolus vulgaris leucoagglutinin (PHA-L) has been used primarily as an anterograde transport tracer in the CNS. We present evidence of PHA-L retrograde transport by rat spinal motoneurons after injection into the triceps brachii. Labelled motoneurons were localized in specific and well-defined neuron pools in the ventral horn. Primary afferent labelling was not seen in the spinal gray matter. Dorsal rhizotomy did not eliminate or decrease motoneuron labelling. The retrograde transport rate was about 8 mm/day. PHA-L can clearly undergo retrograde, as well as anterograde, transport.}, keywords = {lectin, phaseolus vulgaris leucoagglutinin (PHA-L), rat, retrograde transport, spinal motoneuron}, issn = {0304-3940}, doi = {10.1016/0304-3940(88)90559-9}, url = {http://www.ncbi.nlm.nih.gov/pubmed/2453002}, author = {Lee, C. L. and Dennis J. McFarland and Jonathan Wolpaw} } @article {3280, title = {Spinal stretch reflex and cortical evoked potential amplitudes versus muscle stretch amplitude in the monkey arm.}, journal = {Electroencephalography and clinical neurophysiology}, volume = {69}, year = {1988}, month = {04/1988}, pages = {394{\textendash}397}, abstract = {While investigating operant conditioning of the primate spinal stretch reflex (SSR), we studied SSR amplitude and cortical somatosensory evoked potential (SEP) amplitude as stretch amplitude changed in the monkey arm. Initial muscle length and background EMG activity remained constant. With change in stretch amplitude (and proportional change in stretch velocity and acceleration), changes in SSR and SEP amplitudes were respectively 0.75 and 0.66 as great. The lesser change in SSR amplitude may reflect saturation of Ia afferents, while that in SEP amplitude may also reflect participation of other peripheral receptors.}, keywords = {muscle stretch, primate, Somatosensory Cortex, somatosensory evoked potential, spinal reflex, stretch reflex}, issn = {0013-4694}, doi = {10.1016/0013-4694(88)90011-9}, url = {http://www.ncbi.nlm.nih.gov/pubmed/2450738}, author = {Jonathan Wolpaw and Dowman, R.} } @article {3278, title = {T complex hemispheric asymmetries: effects of stimulus intensity.}, journal = {Hearing research}, volume = {34}, year = {1988}, month = {08/1988}, pages = {225{\textendash}232}, abstract = {The T complex component of the human auditory evoked potential (AEP) is thought to be produced in auditory cortex, on the posterior lateral surface of the temporal lobe. Recorded over temporal scalp, it consists of an 80-90 ms positive peak, Ta, and a 120-140 negative peak, Tb. As part of an effort to develop the clinical usefulness of the T complex in assessing auditory cortical function, we studied the effects of change in monaural stimulus intensity (20-80 dB SL) on T complex latency, amplitude, and hemispheric differences in normal adults. Ta and Tb peak latencies decreased as stimulus intensity increased. These latency changes were not dependent on ear or hemisphere. Right hemisphere Ta latency was shorter with contralateral than with ipsilateral stimulation; while left hemisphere Ta latency was not dependent on the ear stimulated. Tb latency was shorter over the left hemisphere, and over the contralateral hemisphere. Ta-b amplitude increased as stimulus intensity increased. This amplitude change was not dependent on ear or hemisphere. Ta-b amplitudes were larger over the right hemisphere and over the contralateral hemisphere. Hemispheric asymmetries were not significantly affected by stimulus intensity.}, keywords = {Reaction Time}, issn = {0378-5955}, doi = {10.1016/0378-5955(88)90002-0}, url = {http://www.ncbi.nlm.nih.gov/pubmed/3170365}, author = {Anthony T. Cacace and Dowman, R. and Jonathan Wolpaw} } @article {3283, title = {Motoneuron response to dorsal root stimulation in anesthetized monkeys after spinal cord transection.}, journal = {Experimental brain research. Experimentelle Hirnforschung. Exp{\'e}rimentation c{\'e}r{\'e}brale}, volume = {68}, year = {1987}, month = {10/1987}, pages = {428{\textendash}433}, abstract = {In preparation for studying the spinal cord alterations produced by operant conditioning of spinal reflexes, we studied peripheral nerve responses to supramaximal dorsal root stimulation in the lumbosacral cord of deeply anesthetized monkeys before and after thoracic cord transection. Except for variable depression in the first few minutes, reflex responses were not reduced or otherwise significantly affected by transection in the hour immediately following the lesion or for at least 50 h. The results suggest that reduction in muscle spindle sensitivity and/or in polysynaptic motoneuron excitation contributes to stretch reflex depression after cord transection.}, keywords = {monosynaptic reflex, primate, Spinal Cord, spinal cord injury, spinal reflex, spinal shock}, issn = {0014-4819}, doi = {10.1007/BF00248809}, url = {http://www.ncbi.nlm.nih.gov/pubmed/3480233}, author = {Jonathan Wolpaw and Lee, C. L.} } @article {3282, title = {Operant conditioning of primate spinal reflexes: the H-reflex.}, journal = {Journal of neurophysiology}, volume = {57}, year = {1987}, month = {02/1987}, pages = {443{\textendash}459}, abstract = {The study of primate memory substrates, the CNS alterations which preserve conditioned responses, requires an experimental model that fulfills two criteria. First, the essential alterations must be in a technically accessible location. Second, they must persist without input from other CNS regions. The spinal cord is the most technically accessible and readily isolated portion of the primate CNS. Recent work has demonstrated that the spinal stretch reflex (SSR), the initial, wholly segmental response to muscle stretch, can be operantly conditioned and suggests that this conditioning may produce persistent spinal alteration. The present study attempted similar operant conditioning of the H-reflex, the electrical analog of the SSR. The primary goals were to demonstrate that spinal reflex conditioning can occur even if the muscle spindle is removed from the reflex arc and to demonstrate conditioning in the lumbosacral cord, which is far preferable to the cervical cord for future studies of neuronal and synaptic mechanisms. Nine monkeys prepared with chronic fine-wire triceps surae (gastrocnemius and soleus) electromyographic (EMG) electrodes were taught by computer to maintain a given level of background EMG activity. At random times, a voltage pulse just above M response (direct muscle response) threshold was delivered to the posterior tibial nerve via a chronically implanted silicon nerve cuff and elicited the triceps surae H-reflex. Under the control mode, reward always followed. Under the HR increases or HR decreases mode, reward followed only if the absolute value of triceps surae EMG from 12 to 22 ms after the pulse (the H-reflex interval) was above (HR increases) or below (HR decreases) a set value. Monkeys completed 3,000-6,000 trials/day over study periods of 2-3 mo. Background EMG and M response amplitude remained stable throughout data collection. H-reflex amplitude remained stable under the control mode. Under the HR increases mode (5 animals) or HR decreases mode (4 animals), H-reflex amplitude (EMG amplitude in the H-reflex interval minus background EMG amplitude) changed appropriately over at least 6 wk. Change appeared to occur in two phases: an abrupt change within the first day, followed by slower change, which continued indefinitely. Change occurred in all three triceps surae muscles (medial and lateral gastrocnemii and soleus). Under the HR increases mode, H-reflex amplitude rose to an average of 213\% of control, whereas under the HR decreases mode it fell to an average of 68\% of control. The results demonstrate that the H-reflex can be operantly conditioned.(ABSTRACT TRUNCATED AT 400 WORDS)}, keywords = {Spinal Cord}, issn = {0022-3077}, url = {http://www.ncbi.nlm.nih.gov/pubmed/3559687}, author = {Jonathan Wolpaw} } @article {3284, title = {Adaptive plasticity in primate spinal stretch reflex: persistence.}, journal = {Journal of neurophysiology}, volume = {55}, year = {1986}, month = {02/1986}, pages = {272{\textendash}279}, abstract = {Monkeys can gradually change the amplitude of the wholly segmental, largely monosynaptic, spinal stretch reflex (SSR) when confronted by a task requiring such change (15-19). Change develops over months and may reverse and redevelop at similarly slow rates. We investigated the persistence of SSR amplitude change over nonperformance periods of up to 38 days. Eight animals with chronic EMG electrodes learned to maintain elbow angle and a given level of biceps background EMG against constant extension torque. At random times, a brief additional extension torque pulse elicited the biceps SSR. In the control mode, reward always followed. Under the SSR increase or SSR decrease mode, reward occurred only if the absolute value of biceps EMG in the SSR interval was above or below a set value. Animals completed 3,000-6,000 trials/day over data-collection periods of 2-17 mo. Animals worked first under the control mode for up to 60 days and then under the SSR increase or SSR decrease mode for up to 274 days. Mode was switched once or twice more (SSR increase to SSR decrease or vice versa) over subsequent months. Animals responded to each SSR increase or SSR decrease mode exposure with gradual mode-appropriate change in SSR amplitude. Mode exposures were interrupted by gaps in performance of 10-38 days. Gaps produced transient 10- to 15\% decreases in SSR amplitude under the control mode. This nonspecific decrease disappeared over the first week of postgap performance. Under the control mode, gaps had no other effects on SSR amplitude.(ABSTRACT TRUNCATED AT 250 WORDS)}, keywords = {Spinal Cord}, issn = {0022-3077}, url = {http://www.ncbi.nlm.nih.gov/pubmed/3950691}, author = {Jonathan Wolpaw and O{\textquoteright}Keefe, J. A. and Noonan, P. A. and Sanders, M. G.} } @article {3285, title = {Adaptive plasticity in the spinal stretch reflex: an accessible substrate of memory?.}, journal = {Cellular and molecular neurobiology}, volume = {5}, year = {1985}, month = {06/1985}, pages = {147{\textendash}165}, abstract = {The study of the substrates of memory in higher vertebrates is one of the major problems of neurobiology. A simple and technically accessible experimental model is needed. Recent studies have demonstrated long-term adaptive plasticity, a form of memory, in the spinal stretch reflex (SSR). The SSR is due largely to a two-neuron monosynaptic arc, the simplest, best-defined, and most accessible pathway in the primate central nervous system (CNS). Monkeys can slowly change SSR amplitude without a change in initial muscle length or alpha motoneuron tone, when reward is made contingent on amplitude. Change occurs over weeks and months and persists for long periods. It is relatively specific to the agonist muscle and affects movement. The salient features of SSR adaptive plasticity, combined with clinical and laboratory evidence indicating spinal cord capacity for intrinsic change, suggest that SSR change eventually involves persistent segmental alteration. If this is the case, SSR plasticity should be a powerful model for studying the neuronal and synaptic substrates of memory in a primate.}, keywords = {Learning, Memory, plasticity, primate, spinal reflex, stretch reflex}, issn = {0272-4340}, doi = {10.1007/BF00711090}, url = {http://www.ncbi.nlm.nih.gov/pubmed/3161616}, author = {Jonathan Wolpaw} } @article {3286, title = {Reduced day-to-day variation accompanies adaptive plasticity in the primate spinal stretch reflex.}, journal = {Neuroscience letters}, volume = {54}, year = {1985}, month = {03/1985}, pages = {165{\textendash}171}, abstract = {Monkeys can change the amplitude of the spinal stretch reflex (SSR), or M1, when reward is made contingent on amplitude. The present study demonstrates that reduced SSR day-to-day variation accompanies such adaptive SSR change. This finding supports the assumption that initial, phase I, SSR change results from contingency-appropriate stabilization of tonic activity in relevant descending spinal cord pathways.}, keywords = {Learning, Memory, plasticity, primate, spinal reflex, stretch reflex}, issn = {0304-3940}, doi = {10.1016/S0304-3940(85)80073-2}, url = {http://www.ncbi.nlm.nih.gov/pubmed/3991057}, author = {Jonathan Wolpaw and O{\textquoteright}Keefe, J. A. and Kieffer, V. A. and Sanders, M. G.} } @article {3288, title = {Adaptive plasticity and diurnal rhythm in the primate spinal stretch reflex are independent phenomena.}, journal = {Brain research}, volume = {300}, year = {1984}, month = {05/1984}, pages = {385{\textendash}391}, abstract = {Recent studies have revealed two phenomena producing considerable variation in amplitude of the initial, purely segmental, largely monosynaptic, response to sudden muscle stretch, the spinal stretch reflex (SSR), without change in background EMG activity or initial muscle length. The first is small and short-term, a modest diurnal rhythm in SSR amplitude. The second is large and long-term, marked adaptive change in SSR amplitude which occurs gradually over weeks and months when animals are rewarded for such change. This second phenomenon may involve persistent segmental alteration, and, if so, could constitute a technically accessible substrate of memory. The present study compared the two phenomena and sought evidence of interaction between them. The diurnal rhythm persisted, without change in phase and with only minimal change in amplitude, despite the occurrence of marked adaptive change. Animals did not utilize the rhythm to increase reward percentage by altering daily performance schedules. These results suggest that the mechanisms of the diurnal rhythm and of adaptive plasticity in SSR amplitude are separate and independent. The diurnal rhythm{\textquoteright}s effect on movement was not altered by adaptive change in SSR amplitude. This effect was comparable to adaptive change{\textquoteright}s effect on movement when both were expressed as change in movement/change in SSR amplitude.}, keywords = {adaptive plasticity, diurnal rhythm, Learning, Memory, primate, stretch reflex}, issn = {0006-8993}, doi = {10.1016/0006-8993(84)90852-7}, url = {http://www.ncbi.nlm.nih.gov/pubmed/6539634}, author = {Jonathan Wolpaw and Noonan, P. A. and O{\textquoteright}Keefe, J. A.} } @article {3287, title = {Adaptive plasticity in the primate spinal stretch reflex: evidence for a two-phase process.}, journal = {The Journal of neuroscience : the official journal of the Society for Neuroscience}, volume = {4}, year = {1984}, month = {11/1984}, pages = {2718{\textendash}2724}, abstract = {Monkeys can slowly increase or decrease the amplitude of the purely spinal, largely monosynaptic portion of the response to sudden muscle stretch, the spinal stretch reflex (SSR), when confronted by a task requiring such change (Wolpaw, J.R., V.A. Kieffer, R.F. Seegal, D.J. Braitman, and M.G. Sanders (1983) Brain Res. 267: 196-200; Wolpaw, J.R., D.J. Braitman, and R.F. Seegal (1983) J. Neurophysiol. 50: 1296-1311). Change occurs without alteration in initial muscle length or in background activity of agonist, antagonist, or synergist muscles. This study uses composite curves to describe in detail the development of SSR amplitude change. It reveals important, previously unexpected features of this development. SSR increase or decrease appears to occur in two distinct phases. Phase I, a nearly immediate 8\% change, occurs within the first 6 hr. Phase II, a 2\%/day change, continues for at least 2 months. Although phase II is much slower than phase I, its final magnitude is far greater. Phase I indicates a nearly immediate change in suprasegmental influence of the segmental arc of the SSR. Because stretch onset time is unpredictable and the SSR occurs before any other possible response, this change in descending activity must be tonic; it must be present continually, day after day, for the 5 to 7 hr/day the animal spends at the task. Phase I produces a rapid and significant increase in reward probability. Thus, it may be readily interpreted as an example of operant conditioning, provoked by the reward contingency.(ABSTRACT TRUNCATED AT 250 WORDS)}, keywords = {Time Factors}, issn = {0270-6474}, url = {http://www.ncbi.nlm.nih.gov/pubmed/6502200}, author = {Jonathan Wolpaw and O{\textquoteright}Keefe, J. A.} } @article {3289, title = {Psychoacoustic and electrophysiologic effects of partial eighth nerve damage.}, journal = {American journal of otolaryngology}, volume = {5}, year = {1984}, month = {02/1984}, pages = {43{\textendash}48}, abstract = {The authors present psychoacoustic and electrophysiologic data concerning a patient with partial damage to the auditory nerve, presumably from a dilated arterial vessel. The lesion was described and documented during neurosurgery for vestibular nerve decompression. Pure tone thresholds, psychoacoustical tuning curves, speech reception ability for spondaic words, maximum word recognition performance for monosyllabic NU-6 word lists, and performance on the synthetic sentence identification test in the ipsilateral and contralateral competing message modalities were normal. Findings consistent with eighth nerve dysfunction, absent contralateral acoustic reflexes, absent or unrecognizable early evoked potentials occurring in the first 10 msec, brainstem auditory evoked potentials (BAEPs), and slight rollover of the performance intensity function for monosyllabic words were obtained on the involved side. In spite of the grossly abnormal BAEPs, two late, presumably cortical, auditory evoked potential components, which occur in the 60 to 250-msec range{\textendash}vertex potential and T complex{\textendash}were present and normal. The findings indicate that the perceptual processes needed for speech reception and recognition and for the appearance of later, presumably cortical-evoked potentials can be preserved despite partial damage to the auditory nerve.}, keywords = {Vestibulocochlear Nerve Diseases}, issn = {0196-0709}, doi = {10.1016/S0196-0709(84)80019-8}, url = {http://www.ncbi.nlm.nih.gov/pubmed/6534193}, author = {Anthony T. Cacace and Goldstein, J. C. and Parnes, S. M. and Satya-Murti, S. and Jonathan Wolpaw} } @article {3290, title = {Adaptive plasticity in primate spinal stretch reflex: behavior of synergist and antagonist muscles.}, journal = {Journal of neurophysiology}, volume = {50}, year = {1983}, month = {12/1983}, pages = {1312{\textendash}1319}, abstract = {Monkeys can gradually change the amplitude of the biceps spinal stretch reflex (SSR) without change in initial muscle length or biceps background electromyographic activity (EMG) (17). We investigated the concurrent behavior of synergist (brachialis and brachioradialis) and antagonist (triceps) muscles. Synergist background EMG remained stable while marked change occurred in biceps SSR amplitude. Triceps background EMG was minimal under all conditions. Thus biceps SSR amplitude change was not due to change in the background activity of closely related muscles. When biceps SSR amplitude changed, synergist SSR amplitude changed similarly but to a lesser extent. Brachialis change averaged 72\% of biceps change, while brachioradialis change averaged 33\%. By indicating that SSR amplitude change is relatively specific to the agonist muscle, this finding eliminates a number of nonspecific mechanisms as possible origins of SSR amplitude change. Thus it supports the potential value of the SSR as a system for studying the neuronal and synaptic bases of memory in the primate central nervous system (CNS).}, keywords = {Spinal Cord}, issn = {0022-3077}, url = {http://www.ncbi.nlm.nih.gov/pubmed/6663328}, author = {Jonathan Wolpaw and Seegal, R. F. and O{\textquoteright}Keefe, J. A.} } @article {3291, title = {Adaptive plasticity in primate spinal stretch reflex: initial development.}, journal = {Journal of neurophysiology}, volume = {50}, year = {1983}, month = {12/1983}, pages = {1296{\textendash}1311}, abstract = {Description of the neuronal and synaptic bases of memory in the vertebrate central nervous system (CNS) requires a CNS stimulus-response pathway that is defined and accessible, has the capacity for adaptive change, and clearly contains the responsible substrates. This study was an attempt to determine whether the spinal stretch reflex (SSR), the initial, purely spinal, portion of the muscle stretch response, which satisfies the first requirement, also satisfies the second, capacity for adaptive change. Monkeys prepared with chronic fine-wire biceps electromyographic (EMG) electrodes were trained to maintain elbow position and a given level of biceps background EMG activity against constant extension torque. At random times, a brief additional extension torque pulse extended the elbow and elicited the biceps SSR. Under the control mode, reward always followed. Under the SSR increases or SSR decreases mode, reward followed only if the absolute value of biceps EMG from 14 to 24 ms after stretch onset (the SSR interval) was above or below a set value. Animals performed 3,000-6,000 trials/day over data-collection periods of up to 15 mo. Background EMG and the initial 30 ms of pulse-induced extension remained stable throughout data collection. Under the SSR increases or SSR decreases mode, SSR amplitude (EMG amplitude in the SSR interval minus background EMG amplitude) changed appropriately. Change was evident in 5-10 days and progressed over at least 4 wk. The SSR increased (SSR increases) to 140-190\% control amplitude or decreased (SSR decreases) to 22-79\%. SSR change did not regress over 12-day gaps in task performance. A second pair of biceps electrodes, monitored simultaneously, supplied comparable data, indicating that SSR amplitude change occurred throughout the muscle. Beyond 40 ms after pulse onset, elbow extension was inversely correlated with SSR amplitude. The delay between the SSR and its apparent effect on movement is consistent with expected motor-unit contraction time. The data demonstrate that the SSR is capable of adaptive change. At present the most likely site(s) of the mechanism of SSR amplitude change are the Ia synapse and/or the muscle spindle. Available related evidence suggests persistent segmental change may in fact come to mediate SSR amplitude change. If so, such segmental change would constitute a technically accessible fragment of a memory.}, keywords = {Spinal Cord}, issn = {0022-3077}, url = {http://www.ncbi.nlm.nih.gov/pubmed/6663327}, author = {Jonathan Wolpaw and Braitman, D. J. and Seegal, R. F.} } @article {3292, title = {Adaptive plasticity in the primate spinal stretch reflex: reversal and re-development.}, journal = {Brain research}, volume = {278}, year = {1983}, month = {11/1983}, pages = {299{\textendash}304}, abstract = {Monkeys can gradually increase or decrease the amplitude of the segmentally mediated spinal stretch reflex (SSR) without change in initial muscle length or background EMG activity. Both increase (under the SSR increases mode) and decrease (under the SSR decreases mode) occur slowly, progressing steadily over weeks. The present study investigated reversal and re-development of SSR amplitude change. Over a period of months, following collection of control data, monkeys were exposed to one mode, then to the other, and then to the first mode again. Development, reversal, and re-development of change all took place over weeks, following very similar courses. These data are consistent with the hypothesis that persistent segmental alteration underlies SSR amplitude change. Such persistent segmental alteration would constitute a technically accessible substrate of memory.}, keywords = {Learning, Memory, plasticity, primate, spinal reflex, stretch reflex}, issn = {0006-8993}, doi = {10.1016/0006-8993(83)90259-7}, url = {http://www.ncbi.nlm.nih.gov/pubmed/6640320}, author = {Jonathan Wolpaw} } @article {3294, title = {Adaptive plasticity in the spinal stretch reflex.}, journal = {Brain research}, volume = {267}, year = {1983}, month = {05/1983}, pages = {196{\textendash}200}, abstract = {Monkeys can change the amplitude of the spinal stretch reflex without change in initial alpha motor neuron tone, as measured by EMG, or in initial muscle length. Change is apparent in 5-10 days, continues to develop over weeks, and persists during inactive periods. Spinal stretch reflex change may be a valuable system for studying the neuronal and synaptic bases of an adaptive change in primate CNS function.}, keywords = {Learning, Memory, plasticity, primate, spinal reflex, stretch reflex}, issn = {0006-8993}, doi = {10.1016/0006-8993(83)91059-4}, url = {http://www.ncbi.nlm.nih.gov/pubmed/6860948}, author = {Jonathan Wolpaw and Kieffer, V. A. and Seegal, R. F. and Braitman, D. J. and Sanders, M. G.} } @article {3293, title = {Late auditory evoked potentials can occur without brain stem potentials.}, journal = {Electroencephalography and clinical neurophysiology}, volume = {56}, year = {1983}, month = {10/1983}, pages = {304{\textendash}308}, abstract = {The sequence of early, middle and late auditory evoked potentials is well known. However, it is unknown whether the late (60-250 msec) potentials can occur independently of the early, brain stem potentials. Therefore, in 6 subjects with markedly abnormal or absent brain stem potentials, we recorded two of the late potentials: the vertex potential and the T-complex. The latter is a putative product of auditory cortex. Both of these potentials were clearly evident in all patients in spite of the absence of or marked abnormalities in brain stem potentials.}, keywords = {Humans}, issn = {0013-4694}, doi = {10.1016/0013-4694(83)90255-9}, url = {http://www.ncbi.nlm.nih.gov/pubmed/6193943}, author = {Satya-Murti, S. and Jonathan Wolpaw and Anthony T. Cacace and Schaffer, C. A.} } @article {3332, title = {Change in short-latency response to limb displacement in primates.}, journal = {Federation proceedings}, volume = {41}, year = {1982}, month = {04/1982}, pages = {2156{\textendash}2159}, abstract = {When a muscle is stretched in an awake, behaving primate the earliest electromyographic (EMG) responses of the muscle consists of several reflex components. The earliest, M1, is mediated entirely at the segmental level and is largely monosynaptic. The next M2, is at least in part the result of an oligosynaptic transcortical loop to control the M1 response remains to be established. If primates can learn to control M1 amplitude, the M1 loop, which is the simplest and most accessible stimulus-response pathway in the primate central nervous system, may serve as a model for the study of mechanisms of memory. Preliminary evidence presented here strongly suggests that primates can control M1 gain without change in prestimulus EMG activity. The mechanisms of such change remain to be determined. Possibilities include change in gamma motor neuron tone, in Ia synaptic function, and in alpha motor neuron recruitment. The usefulness of learned M1 change as a model for memory will depend to a large extent on the nature of the responsible mechanism and on demonstration that the change can eventually become resident at the segmental level, without need for continued descending input.}, keywords = {Reflex, Stretch}, issn = {0014-9446}, url = {http://www.ncbi.nlm.nih.gov/pubmed/7075789}, author = {Jonathan Wolpaw} } @article {3329, title = {Diurnal rhythm in the spinal stretch reflex.}, journal = {Brain research}, volume = {244}, year = {1982}, month = {07/1982}, pages = {365{\textendash}369}, abstract = {We studied primate spinal stretch reflex (SSR) amplitude as a function of time of day. SSR amplitude was greatest around midnight and smallest around noon. The diurnal rhythm was not simply a function of number of trials, or of the lighting cycle. This rhythm offers an opportunity to study the neuronal and synaptic mechanisms producing a diurnal change in CNS function. Its existence indicates that the CNS response to a given limb disturbance, and thus the CNS activity underlying a given performance, varies with time of day.}, keywords = {circadian rhythm, diurnal rhythm, muscle stretch, primate, spinal reflex, stretch reflex}, issn = {0006-8993}, doi = {10.1016/0006-8993(82)90099-3}, url = {http://www.ncbi.nlm.nih.gov/pubmed/6889452}, author = {Jonathan Wolpaw and Seegal, R. F.} } @article {3331, title = {Scalp distribution of human auditory evoked potentials. I. Evaluation of reference electrode sites.}, journal = {Electroencephalography and clinical neurophysiology}, volume = {54}, year = {1982}, month = {07/1982}, pages = {15{\textendash}24}, abstract = {In an attempt to settle the long-standing controversy about the relative activity of nose, sternovertebral (SV), and other commonly used AEP reference sites, we recorded AEPs from a coronal chain of electrodes from the vertex to the tragus, extending down the neck, and from the nose, ear, mastoid process, knee and ankle. All electrodes were referred to a sternovertebral reference balanced to minimize EKG. Voltage gradients and wave forms corresponding to other references were derived by computer. Stimuli were presented at fixed durations after the R wave of the EKG and averages with no stimulus were subtracted from averages with click stimuli to minimize synchronized EKG activity in non-cephalic derivations. Because the activity at a given electrode site cannot be determined in absolute terms, alternative reference sites must be compard by examining the relative location of each site in the total potential field. An indifferent electrode site defined in this manner is one at which the spatial and temporal voltage gradients are minimal over the duration of the activity of interest. AEP voltage gradients in this experiment were steepest in the temporal region, became extremely shallow at locations on the upper neck, and showed no detectable gradients below that point attributable to AEP activity. A gradient of this form was obtained in all subjects, in spite of significant intersubject differences in the magnitude of potentials in nose-SV derivations. Commonly used reference sites on the head such as the nose, ear and mastoid process, were shown to lie in regions of the AEP field characterized by significant voltage gradients over time and spatial location in most subjects. The balanced sternovertebral reference of Stephenson and Gibbs (1951) appears to be the best general choice for AEP recordings.}, keywords = {Sternum}, issn = {0013-4694}, doi = {10.1016/0013-4694(82)90227-9}, url = {http://www.ncbi.nlm.nih.gov/pubmed/6177514}, author = {Jonathan Wolpaw and Wood, C. C.} } @article {3330, title = {Scalp distribution of human auditory evoked potentials. II. Evidence for overlapping sources and involvement of auditory cortex.}, journal = {Electroencephalography and clinical neurophysiology}, volume = {54}, year = {1982}, month = {07/1982}, pages = {25{\textendash}38}, abstract = {The scalp distributions of human auditory evoked potentials (AEPs) between 20 and 250 msec were investigated using non-cephalic reference recordings. AEPs to binaural click stimuli were recorded simultaneously from 20 scalp locations over the right hemisphere in 11 subjects. Computer-generated isovoltage topographic maps at high temporal resolution were used to assess the stability of AEP scalp distributions over time and relate them to major peaks in the AEP wave forms. For potentials between 20 and 60 msec, the results demonstrate a stable scalp distribution of dipolar form that is consistent with sources in primary auditory cortex on the superior temporal plant near the temporoparietal junction. For potentials between 60 and 250 msec, the results demonstrate changes in AEP morphology across electrode locations and changes in scalp distribution over time that lead to two major conclusions. First, AEPs in this latency period are generated by multiple sources which partially overlap in time. Second, one or more regions of auditory cortex contribute significantly to AEPs in this period. Additional data are needed to determine the relative contribution of auditory cortex sources on the superior temporal plane and the lateral temporal surface and to identify AEP sources outside the temporal lobe.}, keywords = {Temporal Lobe}, issn = {0013-4694}, doi = {10.1016/0013-4694(82)90228-0}, url = {http://www.ncbi.nlm.nih.gov/pubmed/6177515}, author = {Wood, C. C. and Jonathan Wolpaw} } @article {3333, title = {Amplitude of responses to perturbation in primate sensorimotor cortex as a function of task.}, journal = {Journal of neurophysiology}, volume = {44}, year = {1980}, month = {12/1980}, pages = {1139{\textendash}1147}, abstract = {1. Monkeys learned to maintain hand position against a range of background forces. Short-latency responses to passive wrist extension or flexion were recorded from units in areas 4, 3, 1, and 2. Response amplitude was studied as a function of background force direction (extension or flexion). 2. For 40\% of the precentral and postcentral responses, response amplitude depended on constant force direction. For these dependent responses, amplitude with background force in one direction averaged 2.8 times amplitude with background force in the opposite direction. 3. Units for which background activity varied with constant force direction were designated task related. Dependent responses from area 4 task-related units were usually larger when background activity was greater and when background force direction matched the direction of the passive movement. 4. Dependent responses from area 4 task-related units occurred significantly later than nondependent responses from the same units. 5. Since most area 4 task-related activity was explicable as a result of peripheral input via the same oligosynaptic path mediating area 4 responses to passive movements (32), the present findings imply that area 4-task-related activity may result in large part from centrally mediated change in the access of short-latency peripheral input to area 4 units. 6. The dependence of responses from non-task-related area 4 units and from non-task-related and task-related postcentral units showed no dominant correlation with background activity or with background force direction. Their dependence appeared to require no explanation other than a change in peripheral input with change in background force direction.}, keywords = {Wrist}, issn = {0022-3077}, url = {http://www.ncbi.nlm.nih.gov/pubmed/7452325}, author = {Jonathan Wolpaw} } @article {3334, title = {Correlations between task-related activity and responses to perturbation in primate sensorimotor cortex.}, journal = {Journal of neurophysiology}, volume = {44}, year = {1980}, month = {12/1980}, pages = {1122{\textendash}1138}, abstract = {1. Monkeys were trained to maintain hand position against a range of constant forces. Short-latency responses to passive wrist extension or flexion, as well as short-latency responses to stretch of a single wrist muscle, were recorded from units in areas 4, 3, 1, and 2. These responses were compared to unit activity during active holding and during active movement. 2. Units related to active holding and to active movement were most common in areas 4 and 2. Three-quarters of these units displayed a specific correlation between their passive and active behaviors. Thus, a unit excited by passive extension was excited during active holding against extension force and excited during an active flexion movement. This behavior is similar to the expected concurrent behavior of muscle stretch receptors. By demonstrating that a significant number of task-related units give qualitatively similar responses to passive extension and passive flexion, the results appear to explain the disagreement among previous studies (5, 9, 36) in regard to area 4 behavior during active and passive movements. 3. Area 4 units responded similarly to passive wrist extension and electromagnetic stretch of a single flexor muscle occurring in the absence of wrist extension, indicating that muscle stretch was important in determining area 4 unit responses to passive movements. 4. The similarity of area 4 behavior to area 2 behavior in active and passive situations, along with the observation that area 2 responses to passive movements occurred several milliseconds earlier than those of area 4, emphasizes the importance of area 2 in motor performance and is consistent with significant area 2 mediation of area 4 responses. 5. Results support the hypothesis of an oligosynaptic transcortical pathway (22, 32, 34), beginning in large part with muscle stretch receptors. Furthermore, the correlation noted between short-latency responses to passive movement and task-related activity suggests that this transcortical pathway not only mediates responses to passive movement but may be responsible, to a significant degree, for task-related activity during undisturbed performance. Thus, active position maintenance and active movement were probably accomplished, at least in part, by increasing and decreasing the influence of this pathway on specific area 4 neurons and thereby producing the patterns of area 4 activity responsible for task performance.}, keywords = {Task Performance and Analysis}, issn = {0022-3077}, url = {http://www.ncbi.nlm.nih.gov/pubmed/6450275}, author = {Jonathan Wolpaw} } @article {3335, title = {Electromagnetic method for in situ stretch of individual muscles.}, journal = {Medical \& biological engineering \& computing}, volume = {18}, year = {1980}, month = {03/1980}, pages = {145{\textendash}152}, abstract = {A technique for stretching individual muscles in intact behaving animals via chronic intramuscular implantation of a permeable slug and use of an external electromagnet to apply force to the slug has been developed for use in the study of the role of sensory input due to muscle stretch in the control of skilled motor activity. This paper is an analysis of the force exerted on a permeable slug by a solenoid, and a discussion of practical aspects of design and control. The force exerted on a slug inside a coil is a function of slug length, cross-sectional area, and magnetisation properties and of coil size, geometry, and current. The force inside the coil may be increased by surrounding the coil with a permeable sleeve and thereby increasing the field strength inside the coil.}, keywords = {Electromagnetic force, Electromagnetic muscle strength, Motor control, Muscle stimulation, Sensorimotor system, Stimulation with force}, issn = {0140-0118}, doi = {10.1007/BF02443289}, url = {http://www.ncbi.nlm.nih.gov/pubmed/6771473}, author = {Colburn, T. R. and Vaughn, W. and Christensen, J. L. and Jonathan Wolpaw} } @article {3337, title = {Electromagnetic muscle stretch strongly excites sensorimotor cortex neurons in behaving primates.}, journal = {Science (New York, N.Y.)}, volume = {203}, year = {1979}, month = {02/1979}, pages = {465{\textendash}467}, abstract = {Responses of single units in primary motor and sensory cortex of behaving primates to electromagnetic stretch of the muscle flexor carpi ulnaris are comparable in latency and intensity to responses to wrist extension. Thus, muscle stretch appears to be a major factor in cortical response to limb displacement during performance and probably has an important role in motor control at the cortical level.}, keywords = {Proprioception}, issn = {0036-8075}, doi = {10.1126/science.104385}, url = {http://www.ncbi.nlm.nih.gov/pubmed/104385}, author = {Jonathan Wolpaw} } @article {3338, title = {Gyral impressions in the skull as a guide to cortical topography in chronic transdural unit recording.}, journal = {Brain research}, volume = {160}, year = {1979}, month = {01/1979}, pages = {505{\textendash}508}, keywords = {Skull}, issn = {0006-8993}, doi = {10.1016/0006-8993(79)91076-X}, url = {http://www.ncbi.nlm.nih.gov/pubmed/105781}, author = {Jonathan Wolpaw} } @article {3336, title = {Single unit activity vs. amplitude of the epidural evoked potential in primary auditory cortex of awake cats.}, journal = {Electroencephalography and clinical neurophysiology}, volume = {47}, year = {1979}, month = {09/1979}, pages = {372{\textendash}376}, abstract = {The study investigated, in primary auditory cortex (AI) of awake cats, the relationship over a range of stimuli between the amplitude and latency of the initial positive deflection (P1) of the primary evoked potential and the intensity of concurrent underlying evoked single unit activity. Epidural evoked potentials and extracellular responses of 155 single units to monaural 100 musec clicks ranging from 45 to 110 dB were recorded. At low stimulus levels, considerable unit response could occur with a very small P1. At middle stimulus levels, unit response was directly proportional to P1 amplitude. At higher stimulus levels, P1 amplitude continued to increase while unit response began to saturate.}, keywords = {Reaction Time}, issn = {0013-4694}, doi = {10.1016/0013-4694(79)90288-8}, url = {http://www.ncbi.nlm.nih.gov/pubmed/90607}, author = {Jonathan Wolpaw} } @article {3341, title = {Acute and chronic antiepileptic drug effect on the T complex interhemispheric latency difference.}, journal = {Epilepsia}, volume = {19}, year = {1978}, month = {02/1978}, pages = {99{\textendash}107}, abstract = {Antiepileptic drugs may significantly affect brain function in the absence of overt toxicity or excessive serum drug levels. A clinically practical monitor of such effects would be of considerable value in clinical research and practice. Auditory evoked responses were recorded from patients before and after initiation of antiepileptic drug therapy and from patients on therapy for at least 1 year. T complexes were isolated (Wolpaw and Penry, 1975), and Ta peak ipsilateral versus contralateral latency differences were determined. In 13 patients beginning phenobarbital, more than half the postdrug determinations were significantly increased over the patients{\textquoteright} predrug control values in the first 30 days and thereafter, and grossly abnormal values were frequent. In 10 patients beginning phenytoin, latency differences were similarly increased, although grossly abnormal values were less common. In 2 patients beginning clonazepam, 14 of 15 postdrug determinations were significantly increased, and five were grossly abnormal. In no patients were serum drug levels above the therapeutic ranges. In 40 patients chronically treated with phenobarbital or primidone, phenytoin, or a combination of phenytoin and phenobarbital or primidone, abnormal latency differences were obtained in 33, 36, and 29\% of the determinations, respectively. The Ta peak ipsilateral versus contralateral latency difference is an internally controlled correlate of higher level specific sensory function which is sensitive to acute and chronic therapy with phenobarbital, phenytoin, or clonazepam in therapeutic dosages. With further investigation, it may be of clinical use.}, keywords = {Antiepileptic drug effects, Auditory evoked response, Hemispheric difference, T complex}, issn = {0013-9580}, doi = {10.1111/j.1528-1157.1978.tb05017.x}, url = {http://www.ncbi.nlm.nih.gov/pubmed/624272}, author = {Jonathan Wolpaw and Penry, J. K.} } @article {3339, title = {Effects of ethanol, caffeine, and placebo on the auditory evoked response.}, journal = {Electroencephalography and clinical neurophysiology}, volume = {44}, year = {1978}, month = {05/1978}, pages = {568{\textendash}574}, abstract = {A previous paper (Wolpaw and Penry 1975) described separation of the 75-250 msec portion of the AER into N1P2, a product of large areas of cortex, and the T complex, probably a product of secondary auditory cortex. With monaural stimulation, the T complex is larger and earlier on the side contralateral to stimulation and on the right side. Thirty-one normal adults received 3 oz. of ethanol, 300 mg of caffeine, or placebo. Monaural AERs were recorded before intake in all cases, 1 and 4 h after ethanol and 80 min after caffeine or placebo. Blood levels of ethanol and caffeine were measured. Placebo produced mild (20\%) decreases in N1P2 amplitude. Caffeine did not decrease N1P2 amplitude. It did produce a statistically significant 2\% decrease in Ta peak latency. Ethanol reduced N1P2 amplitude markedly at 1 h and mildly at 4 h. Placebo did not affect hemispheric differences. Caffeine significantly increased the Ta peak ipsilateral vs. contralateral latency difference in 3 of 7 individuals. Ethanol significantly increased it in 3 of 6 subjects at 1 h and in 7 of 10 at 4 h, primarily by increasing ipsilateral latencies.}, keywords = {Placebos}, issn = {0013-4694}, doi = {10.1016/0013-4694(78)90124-4}, url = {http://www.ncbi.nlm.nih.gov/pubmed/77763}, author = {Jonathan Wolpaw and Penry, J. K.} } @article {3340, title = {Electromagnetic stretch of individual muscles in behaving primates.}, journal = {Brain research}, volume = {141}, year = {1978}, month = {02/1978}, pages = {193{\textendash}196}, keywords = {Wakefulness}, issn = {0006-8993}, doi = {10.1016/0006-8993(78)90630-3}, url = {http://www.ncbi.nlm.nih.gov/pubmed/414823}, author = {Jonathan Wolpaw and Colburn, T. R.} } @article {3342, title = {Hemispheric differences in the auditory evoked response.}, journal = {Electroencephalography and clinical neurophysiology}, volume = {43}, year = {1977}, month = {07/1977}, pages = {99{\textendash}102}, abstract = {The separation of the 80-250 msec portion of the AER to click stimulation into N1P2, produced by large areas of cortex, and the T complex, probably produced by secondary auditory cortex, was recently described (Wolpaw and Penry 1975). The present study investigated the ipsilateral vs. contralateral and right vs. left hemispheric differences in N1P2 and T complex latencies and amplitudes. One msec clicks at 60 dB above threshold were presented at 4.7 sec intervals monaurally to 32 normal adults and binaurally to 13 of the 32. AERs were recorded from vertex and temporal referred to a balanced non-cephalic reference electrode. For monaural stimulation, N1P2 and T complex amplitudes were significantly greater and T complex latency was significantly less over the contralateral and right hemispheres. The ipsilateral vs. contralateral and right vs. left hemispheric amplitude differences were significanlty greater for the T complex than for N1P2. Binaural results, which provided in additional measure of right vs. left hemispheric differences, were in agreement with the monaural findings. The results are consistent with neurophysiologic and behavioral findings in regard to ipsilateral vs. contralateral and right vs. left hemispheric differences and support the hypothesis that the T complex is produced by secondary auditory cortex.}, keywords = {Reaction Time}, issn = {0013-4694}, doi = {10.1016/0013-4694(77)90200-0}, url = {http://www.ncbi.nlm.nih.gov/pubmed/68878}, author = {Jonathan Wolpaw and Penry, J. K.} } @article {3343, title = {A temporal component of the auditory evoked response.}, journal = {Electroencephalography and clinical neurophysiology}, volume = {39}, year = {1975}, month = {12/1975}, pages = {609{\textendash}620}, abstract = {We studied the 75-225 msec portion of the auditory evoked response (AER) in 32 normal adults at vertex (Cz) and temporal (T3 and T4) placements referred to a balanced, noncephalic reference electrode using a monaural 1 msec click stimulus delivered every 4.7 sec at 60 dB above threshold. The tape-recorded EEG was filtered at 1-25 c/sec, and 128 individual responses were summed, sampling every 0.5 msec for 250 msec post-stimulation. The Cz AERs showed the classic vertex response, a negative peak, N1, at 100 msec, followed by a positive peak, P2, at 160-200 msec. The T3 and T4 AERs were similar to the Cz AERs from 0 to 80 msec and from 200 to 250 msec. They differed significantly from the Cz AERs from 80 to 200 msec. The difference is best explained by the hypothesis that the Cz AERs consisted of N1P2, while the T3 and T4 AERs consisted of N1P2 plus an additional superimposed component, which we called the T complex, comprising a positive peak, Ta, at 105-110 msec, and a negative peak, Tb, at 150-160 msec. By computer, the corresponding Cz and T3 or T4 AERs were normalized to equalize their amplitudes, and the former was subtracted from the latter, thus isolating the T complex. The Ta peak was found to occur 1.5 +/- 1.6 msec earlier at the electrode contralateral to stimulation, and 2.2 +/- 4.0 msec earlier at the T4 (right) electrode. Both differences were statistically significant. The T complex amplitude was greater at the electrode contralateral to stimulation and at the T4 electrode. These findings appear to resolve current controversies concerning the form of the temporal AER. While N1P2 is apparently a product of widespread areas of cortex, we conclude that the T complex is probably a product of secondary auditory cortex.}, keywords = {Time Factors}, issn = {0013-4694}, doi = {10.1016/0013-4694(75)90073-5}, url = {http://www.ncbi.nlm.nih.gov/pubmed/53139}, author = {Jonathan Wolpaw and Penry, J. K.} } @article {3344, title = {Tongue necrosis attributed to ergotamine in temporal arteritis.}, journal = {JAMA : the journal of the American Medical Association}, volume = {225}, year = {1973}, month = {07/1973}, pages = {514{\textendash}515}, abstract = {On two occasions, a woman with temporal arteritis developed tongue cyanosis and numbness shortly after the administration of ergotamine tartrate. Partial necrosis of the tongue resulted. Presumably, the lingual artery compromise, frequently present in temporal arteritis, was made symptomatic by the vasoconstrictive action of ergotamine tartrate.}, keywords = {Tongue Diseases}, issn = {0098-7484}, doi = {10.1001/jama.1973.03220320044012}, url = {http://www.ncbi.nlm.nih.gov/pubmed/4740340}, author = {Jonathan Wolpaw and Brottem, J. L. and Martin, H. L.} } @article {3346, title = {The aetiology of retrograde amnesia.}, journal = {Lancet}, volume = {2}, year = {1971}, month = {08/1971}, pages = {356{\textendash}358}, abstract = {To date, hypotheses of the {\ae}tiology of retrograde amnesia have focused on anatomical effects of traumatic lesions and on the presumed existence of short-term memory. The invariable association of retrograde amnesia with post-traumatic amnesia has been ignored as a clue to the origin of retrograde amnesia. It is suggested here that post-traumatic amnesia, by depriving preceding memories of a large proportion of their associated memories, leads to retrograde amnesia. The hypothesis accounts for the occurrence of retrograde amnesia in so many different situations and allows for the existence of very long retrograde amnesia.}, keywords = {Wounds and Injuries}, issn = {0140-6736}, url = {http://www.ncbi.nlm.nih.gov/pubmed/4105052}, author = {Jonathan Wolpaw} } @article {3345, title = {Aetiology of retrograde amnesia.}, journal = {Lancet}, volume = {2}, year = {1971}, month = {10/1971}, pages = {976}, keywords = {Wounds and Injuries}, issn = {0140-6736}, url = {http://www.ncbi.nlm.nih.gov/pubmed/4107924}, author = {Jonathan Wolpaw} }