@article {4297, title = {Operant Condition of the Flexor Carpi Radialis H-reflex}, journal = {Archives of Physical Medicine and Rehabilitation }, volume = {101}, year = {2020}, month = {12/2020}, chapter = {145}, abstract = {Operant conditioning of the largely monosynaptic H-reflex is a targeted and non-invasive therapeutic intervention for people with motor dysfunction after spinal cord injury and possibly stroke.1,2,3 It can complement other therapies and has no known adverse side effects. To date, H-reflex operant conditioning has focused on the leg. Here, we extend it to the arm by asking participants to either increase or decrease the flexor carpi radialis (FCR) H-reflex. In addition, we examine concurrent changes in brain activity by recording electroencephalographic activity (EEG).}, keywords = {BCI, FCR, H-Reflex, operant conditioning, Rehabilitation}, doi = {10.1016/j.apmr.2020.10.062}, url = {https://www.archives-pmr.org/article/S0003-9993(20)31081-9/abstract}, author = {J Norton and T Vaughan and D Gemoets and S Heckman and S.D. Toliou and J Carp and J.R. 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 {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} } @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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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 {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.} }