02285nas a2200253 4500008004100000022001400041245007600055210006900131260001200200300001400212490000800226520146600234653001001700653002901710653001301739653001101752653002101763653002201784653004401806100002001850700002401870700002201894856011501916 2023 eng d a1432-110600aEffects of active and sham tDCS on the soleus H-reflex during standing.0 aEffects of active and sham tDCS on the soleus Hreflex during sta c06/2023 a1611-16220 v2413 a

Weak transcranial direct current stimulation (tDCS) is known to affect corticospinal excitability and enhance motor skill acquisition, whereas its effects on spinal reflexes in actively contracting muscles are yet to be established. Thus, in this study, we examined the acute effects of Active and Sham tDCS on the soleus H-reflex during standing. In fourteen adults without known neurological conditions, the soleus H-reflex was repeatedly elicited at just above M-wave threshold throughout 30 min of Active (N = 7) or Sham (N = 7) 2-mA tDCS over the primary motor cortex in standing. The maximum H-reflex (H) and M-wave (M) were also measured before and immediately after 30 min of tDCS. The soleus H-reflex amplitudes became significantly larger (by 6%) ≈1 min into Active or Sham tDCS and gradually returned toward the pre-tDCS values, on average, within 15 min. With Active tDCS, the amplitude reduction from the initial increase appeared to occur more swiftly than with Sham tDCS. An acute temporary increase in the soleus H-reflex amplitude within the first minute of Active and Sham tDCS found in this study indicates a previously unreported effect of tDCS on the H-reflex excitability. The present study suggests that neurophysiological characterization of Sham tDCS effects is just as important as investigating Active tDCS effects in understanding and defining acute effects of tDCS on the excitability of spinal reflex pathways.

10aAdult10aEvoked Potentials, Motor10aH-Reflex10aHumans10aMuscle, Skeletal10aStanding Position10aTranscranial Direct Current Stimulation1 aMcCane, Lynn, M1 aWolpaw, Jonathan, R1 aThompson, Aiko, K uhttps://www.neurotechcenter.org/publications/2023/effects-active-and-sham-tdcs-soleus-h-reflex-during-standing03030nas a2200265 4500008004100000022001400041245016500055210006900220260001600289490000700305520208500312653002502397653002102422653001302443653001102456653002102467653002202488653002602510100002502536700001702561700002202578700002202600700002202622856012002644 2023 eng d a1741-255200aMethods for automated delineation and assessment of EMG responses evoked by peripheral nerve stimulation in diagnostic and closed-loop therapeutic applications.0 aMethods for automated delineation and assessment of EMG response c2023 Jul 210 v203 a

Surface electromyography measurements of the Hoffmann (H-) reflex are essential in a wide range of neuroscientific and clinical applications. One promising emerging therapeutic application is H-reflex operant conditioning, whereby a person is trained to modulate the H-reflex, with generalized beneficial effects on sensorimotor function in chronic neuromuscular disorders. Both traditional diagnostic and novel realtime therapeutic applications rely on accurate definitions of the H-reflex and M-wave temporal bounds, which currently depend on expert case-by-case judgment. The current study automates such judgments.Our novel wavelet-based algorithm automatically determines temporal extent and amplitude of the human soleus H-reflex and M-wave. In each of 20 participants, the algorithm was trained on data from a preliminary 3 or 4 min recruitment-curve measurement. Output was evaluated on parametric fits to subsequent sessions' recruitment curves (92 curves across all participants) and on the conditioning protocol's subsequent baseline trials (∼1200 per participant) performed near. Results were compared against the original temporal bounds estimated at the time, and against retrospective estimates made by an expert 6 years later.Automatic bounds agreed well with manual estimates: 95% lay within ±2.5 ms. The resulting H-reflex magnitude estimates showed excellent agreement (97.5% average across participants) between automatic and retrospective bounds regarding which trials would be considered successful for operant conditioning. Recruitment-curve parameters also agreed well between automatic and manual methods: 95% of the automatic estimates of the current required to elicitfell within±1.4%of the retrospective estimate; for the 'threshold' current that produced an M-wave 10% of maximum, this value was±3.5%.Such dependable automation of M-wave and H-reflex definition should make both established and emerging H-reflex protocols considerably less vulnerable to inter-personnel variability and human error, increasing translational potential.

10aElectric Stimulation10aElectromyography10aH-Reflex10aHumans10aMuscle, Skeletal10aPeripheral Nerves10aRetrospective Studies1 aMcKinnon, Michael, L1 aHill, Jeremy1 aCarp, Jonathan, S1 aDellenbach, Blair1 aThompson, Aiko, K uhttps://www.neurotechcenter.org/publications/2023/methods-automated-delineation-and-assessment-emg-responses-evoked03130nas a2200313 4500008004100000022001400041245013900055210006900194260001500263520206900278653002002347653002602367653002102393653002202414653001302436653001102449653002702460653002502487100001702512700001702529700001902546700002402565700002302589700002102612700001402633700002402647700002202671856012302693 2022 eng d a1940-087X00aThe Evoked Potential Operant Conditioning System (EPOCS): A Research Tool and an Emerging Therapy for Chronic Neuromuscular Disorders.0 aEvoked Potential Operant Conditioning System EPOCS A Research To c2022 08 253 a

The Evoked Potential Operant Conditioning System (EPOCS) is a software tool that implements protocols for operantly conditioning stimulus-triggered muscle responses in people with neuromuscular disorders, which in turn can improve sensorimotor function when applied appropriately. EPOCS monitors the state of specific target muscles-e.g., from surface electromyography (EMG) while standing, or from gait cycle measurements while walking on a treadmill-and automatically triggers calibrated stimulation when pre-defined conditions are met. It provides two forms of feedback that enable a person to learn to modulate the targeted pathway's excitability. First, it continuously monitors ongoing EMG activity in the target muscle, guiding the person to produce a consistent level of activity suitable for conditioning. Second, it provides immediate feedback of the response size following each stimulation and indicates whether it has reached the target value. To illustrate its use, this article describes a protocol through which a person can learn to decrease the size of the Hoffmann reflex-the electrically-elicited analog of the spinal stretch reflex-in the soleus muscle. Down-conditioning this pathway's excitability can improve walking in people with spastic gait due to incomplete spinal cord injury. The article demonstrates how to set up the equipment; how to place stimulating and recording electrodes; and how to use the free software to optimize electrode placement, measure the recruitment curve of direct motor and reflex responses, measure the response without operant conditioning, condition the reflex, and analyze the resulting data. It illustrates how the reflex changes over multiple sessions and how walking improves. It also discusses how the system can be applied to other kinds of evoked responses and to other kinds of stimulation, e.g., motor evoked potentials to transcranial magnetic stimulation; how it can address various clinical problems; and how it can support research studies of sensorimotor function in health and disease.

10aChronic Disease10aConditioning, Operant10aElectromyography10aEvoked Potentials10aH-Reflex10aHumans10aNeuromuscular Diseases10aSpinal Cord Injuries1 aHill, Jeremy1 aGupta, Disha1 aEftekhar, Amir1 aBrangaccio, Jodi, A1 aNorton, James, J S1 aMcLeod, Michelle1 aFake, Tim1 aWolpaw, Jonathan, R1 aThompson, Aiko, K uhttps://www.neurotechcenter.org/publications/2022/evoked-potential-operant-conditioning-system-epocs-research-tool-and02454nas a2200265 4500008004100000022001400041245007300055210006900128260001200197300001400209490000800223520163500231653001001866653001601876653002101892653001301913653001101926653002001937653002101957100001801978700002401996700002602020700002202046856012002068 2022 eng d a1432-110600aSoleus H-reflex modulation during a double-legged drop landing task.0 aSoleus Hreflex modulation during a doublelegged drop landing tas c04/2022 a1093-11030 v2403 a

Muscle spindle afferent feedback is modulated during different phases of locomotor tasks in a way that facilitates task goals. However, only a few studies have studied H-reflex modulation during landing. This study aimed to characterize soleus (SOL) H-reflex modulation during the flight and early landing period of drop landings. Since landing presumably involves a massive increase in spindle afferent firing due to rapid SOL muscle stretching, we hypothesized H-reflex size would decrease near landing reflecting neural modulation to prevent excessive motoneuron excitation. The soleus H-reflex was recorded during drop landings from a 30 cm height in nine healthy adults. Electromyography (SOL, tibialis anterior (TA), medial gastrocnemius, and vastus lateralis), ankle and knee joint motion and ground reaction force were recorded during landings. Tibial nerve stimulation was timed to elicit H-reflexes during the flight and early ground contact period (five 30 ms Bins from 90 ms before to 60 ms after landing). The H-reflexes recorded after landing (0-30 and 30-60 ms) were significantly smaller (21-36% less) than that recorded during the flight periods (90-0 ms before ground contact; P ≤ 0.004). The decrease in H-reflex size not occurring until after ground contact indicates a time-critical modulation of reflex gain during the last 30 ms of flight (i.e., time of tibial nerve stimulation). H-reflex size reduction after ground contact supports a probable neural strategy to prevent excessive reflex-mediated muscle activation and thereby facilitates appropriate musculotendon and joint stiffness.

10aAdult10aAnkle Joint10aElectromyography10aH-Reflex10aHumans10aMuscle Spindles10aMuscle, Skeletal1 aLyle, Mark, A1 aMcLeod, Michelle, M1 aPouliot, Bridgette, A1 aThompson, Aiko, K uhttps://www.neurotechcenter.org/publications/2022/soleus-h-reflex-modulation-during-double-legged-drop-landing-task02012nas a2200229 4500008004100000022001400041245004900055210004800104260001200152300001100164490000800175520137600183653003401559653001301593653002501606653001901631653002301650653001801673100002201691700002101713856004801734 2015 eng d a1875-785500aTargeted neuroplasticity for rehabilitation.0 aTargeted neuroplasticity for rehabilitation c03/2015 a157-720 v2183 a

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'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.

10aactivity-dependent plasticity10aH-Reflex10aoperant conditioning10aRehabilitation10aspinal cord injury10aspinal reflex1 aThompson, Aiko, K1 aWolpaw, Jonathan uhttp://www.ncbi.nlm.nih.gov/pubmed/2589013602145nas a2200217 4500008004100000022001400041245008500055210006900140260001200209300000700221490000600228520150000234653001301734653002401747653001501771653002301786653002701809100002201836700002101858856004801879 2014 eng d a1662-514500aOperant conditioning of spinal reflexes: from basic science to clinical therapy.0 aOperant conditioning of spinal reflexes from basic science to cl c03/2014 a250 v83 aNew 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'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.10aH-Reflex10alearning and memory10aLocomotion10aspinal cord injury10aspinal cord plasticity1 aThompson, Aiko, K1 aWolpaw, Jonathan uhttp://www.ncbi.nlm.nih.gov/pubmed/2467244101203nas a2200277 4500008004100000022001400041245009000055210006900145260001200214300001000226490000700236520041500243653001200658653002600670653001300696653001100709653001700720653002100737653002400758653001100782653001600793653002500809100002200834700002100856856004800877 2014 eng d a1538-300800aThe simplest motor skill: mechanisms and applications of reflex operant conditioning.0 asimplest motor skill mechanisms and applications of reflex opera c04/2014 a82-900 v423 aOperant 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.10aAnimals10aConditioning, Operant10aH-Reflex10aHumans10aMotor Skills10aMuscle, Skeletal10aNeuronal Plasticity10aReflex10aSpinal Cord10aSpinal Cord Injuries1 aThompson, Aiko, K1 aWolpaw, Jonathan uhttp://www.ncbi.nlm.nih.gov/pubmed/24508738