02092nas a2200217   4500008004100000022001400041245009800055210006900153260001200222300001100234490000700245520143300252653001301685653001501698653002301713653002701736653002001763100002201783700002101805856004801826       2015                        eng d  a1089-409800aRestoring walking after spinal cord injury: operant conditioning of spinal reflexes can help.0 aRestoring walking after spinal cord injury operant conditioning   c04/2015  a203-150 v213 a<p>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.</p>10aLearning10aLocomotion10aspinal cord injury10aspinal cord plasticity10aspinal reflexes1 aThompson, Aiko, K1 aWolpaw, Jonathan  uhttp://www.ncbi.nlm.nih.gov/pubmed/2463695402675nas a2200325   4500008004100000022001400041245010000055210006900155260001200224300001200236490000800248520178700256653001202043653002602055653001102081653001302092653001302105653001502118653000902133653000902142653002502151653002502176100001302201700001302214700001902227700001302246700002102259700002102280856004802301       2014                        eng d  a1522-159800aLocomotor impact of beneficial or nonbeneficial H-reflex conditioning after spinal cord injury.0 aLocomotor impact of beneficial or nonbeneficial Hreflex conditio  c03/2014  a1249-580 v1113 aWhen 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.10aAnimals10aConditioning, Operant10aFemale10aH-Reflex10aLearning10aLocomotion10aMale10aRats10aRats, Sprague-Dawley10aSpinal Cord Injuries1 aChen, Yi1 aChen, Lu1 aLiu, Rongliang1 aWang, Yu1 aChen, Xiang Yang1 aWolpaw, Jonathan  uhttp://www.ncbi.nlm.nih.gov/pubmed/2437128802145nas 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/2467244102425nas a2200289   4500008004100000022001400041245008700055210006900142260001200211300001200223490000800235520161100243653002601854653001301880653001501893653001101908653001801919653001901937653002301956653002701979100001302006700001302019700001302032700002102045700002102066856004802087       2014                        eng d  a1522-159800aPersistent beneficial impact of H-reflex conditioning in spinal cord-injured rats.0 aPersistent beneficial impact of Hreflex conditioning in spinal c  c11/2014  a2374-810 v1123 a<p>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 [±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.</p>10aH-reflex conditioning10aLearning10aLocomotion10aMemory10aMotor control10aRehabilitation10aspinal cord injury10aspinal cord plasticity1 aChen, Yi1 aChen, Lu1 aWang, Yu1 aWolpaw, Jonathan1 aChen, Xiang Yang  uhttp://www.ncbi.nlm.nih.gov/pubmed/2514354202449nas a2200241   4500008004100000022001400041245010300055210006900158260001200227300001600239490000700255520172600262653001301988653001502001653002502016653001502041653001902056653001502075100002302090700002502113700002102138856004802159       2013                        eng d  a1529-240100aOperant conditioning of a spinal reflex can improve locomotion after spinal cord injury in humans.0 aOperant conditioning of a spinal reflex can improve locomotion a  c02/2013  a2365–23750 v333 aOperant 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's particular deficits, and might thereby complement other rehabilitation methods.10aLearning10aLocomotion10aoperant conditioning10aplasticity10aRehabilitation10aspasticity1 aThompson, Aiko, K.1 aPomerantz, Ferne, R.1 aWolpaw, Jonathan  uhttp://www.ncbi.nlm.nih.gov/pubmed/2339266601738nas a2200241   4500008004100000022001400041245009800055210006900153260001200222300001400234490000700248520099700255653001501252653003101267653001801298653001401316653003001330100002101360700002301381700002101404700002301425856004801448       2012                        eng d  a1097-459800aH-reflex modulation in the human medial and lateral gastrocnemii during standing and walking.0 aHreflex modulation in the human medial and lateral gastrocnemii   c01/2012  a116–1250 v453 aINTRODUCTION:
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.10aLocomotion10aphase-dependent modulation10aspinal reflex10asynergist10atask-dependent modulation1 aMakihara, Yukiko1 aSegal, Richard, L.1 aWolpaw, Jonathan1 aThompson, Aiko, K.  uhttp://www.ncbi.nlm.nih.gov/pubmed/2219031701519nas a2200301   4500008004100000022001400041245009500055210006900150260001200219300001400231490001700245520064100262653001300903653002400916653001500940653001500955653002400970653001900994653002301013100002101036700001301057700001301070700001901083700002301102700002301125700002101148856004801169       2010                        eng d  a1749-663200aReflex conditioning: a new strategy for improving motor function after spinal cord injury.0 aReflex conditioning a new strategy for improving motor function   c06/2010  aE12–E210 v1198 Suppl 13 aSpinal 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.10aH-Reflex10alearning and memory10aLocomotion10aplasticity10areflex conditioning10aRehabilitation10aspinal cord injury1 aChen, Xiang Yang1 aChen, Yi1 aWang, Yu1 aThompson, Aiko1 aCarp, Jonathan, S.1 aSegal, Richard, L.1 aWolpaw, Jonathan  uhttp://www.ncbi.nlm.nih.gov/pubmed/2059053401903nas a2200301   4500008004100000022001400041245010700055210006900162260001200231300001800243490000700261520101900268653002601287653001301313653001501326653001101341653001801352653001901370653002301389653002701412100001301439700002101452700002101473700001301494700002501507700002101532856004801553       2006                        eng d  a1529-240100aOperant conditioning of H-reflex can correct a locomotor abnormality after spinal cord injury in rats.0 aOperant conditioning of Hreflex can correct a locomotor abnormal  c11/2006  a12537–125430 v263 a<p>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.</p>10aH-reflex conditioning10aLearning10aLocomotion10aMemory10aMotor control10aRehabilitation10aspinal cord injury10aspinal cord plasticity1 aChen, Yi1 aChen, Xiang Yang1 aJakeman, Lyn, B.1 aChen, Lu1 aStokes, Bradford, T.1 aWolpaw, Jonathan  uhttp://www.ncbi.nlm.nih.gov/pubmed/1713541502190nas a2200253   4500008004100000022001400041245009500055210006900150260001200219300001600231490000800247520145200255653001301707653001501720653001101735653001501746653001601761100002501777700001901802700002201821700002101843700002401864856004801888       2006                        eng d  a1388-245700aPlastic changes in the human H-reflex pathway at rest following skillful cycling training.0 aPlastic changes in the human Hreflex pathway at rest following s  c08/2006  a1682–16910 v1173 aOBJECTIVE:
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.10aH-Reflex10aLocomotion10aMemory10aplasticity10aSpinal Cord1 aMazzocchio, Riccardo1 aKitago, Tomoko1 aLiuzzi, Gianpiero1 aWolpaw, Jonathan1 aCohen, Leonardo, G.  uhttp://www.ncbi.nlm.nih.gov/pubmed/1679333302708nas a2200289   4500008004100000022001400041245010300055210006900158260001200227300001600239490000700255520184500262653002602107653001302133653001502146653002502161653001802186653001902204653002702223100001302250700002102263700002102284700001902305700002502324700002102349856004802370       2005                        eng d  a1529-240100aThe interaction of a new motor skill and an old one: H-reflex conditioning and locomotion in rats.0 ainteraction of a new motor skill and an old one Hreflex conditio  c07/2005  a6898–69060 v253 aNew 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.10aH-reflex conditioning10aLearning10aLocomotion10amemory consolidation10aMotor control10aRehabilitation10aspinal cord plasticity1 aChen, Yi1 aChen, Xiang Yang1 aJakeman, Lyn, B.1 aSchalk, Gerwin1 aStokes, Bradford, T.1 aWolpaw, Jonathan  uhttp://www.ncbi.nlm.nih.gov/pubmed/16033899