%0 Journal Article %J Muscle & nerve %D 2013 %T Soleus H-reflex operant conditioning changes the H-reflex recruitment curve. %A Thompson, Aiko K. %A Xiang Yang Chen %A Jonathan Wolpaw %K motor learning %K plasticity %K Rehabilitation %K Spinal Cord %X 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. %B Muscle & nerve %V 47 %P 539–544 %8 04/2013 %G eng %U http://www.ncbi.nlm.nih.gov/pubmed/23281107 %R 10.1002/mus.23620 %0 Journal Article %J The Journal of neuroscience : the official journal of the Society for Neuroscience %D 2009 %T Acquisition of a simple motor skill: task-dependent adaptation plus long-term change in the human soleus H-reflex. %A Thompson, Aiko K. %A Xiang Yang Chen %A Jonathan Wolpaw %K H-Reflex %K motor learning %K motor skill %K operant conditioning %K plasticity %K Spinal Cord %X 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. %B The Journal of neuroscience : the official journal of the Society for Neuroscience %V 29 %P 5784–5792 %8 05/2009 %G eng %U http://www.ncbi.nlm.nih.gov/pubmed/19420246 %R 10.1523/JNEUROSCI.4326-08.2009