Soleus H‐reflex operant conditioning changes the H‐reflex recruitment curve

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. Muscle Nerve 47: [?show $1534v]–[?show $1535v], 2013