Soleus H-reflex operant conditioning changes the H-reflex recruitment curve
Related Experiment Video
Updated: May 15, 2026

The Evoked Potential Operant Conditioning System (EPOCS): A Research Tool and an Emerging Therapy for Chronic Neuromuscular Disorders
Published on: August 25, 2022
Aiko K Thompson1, Xiang Yang Chen, Jonathan R Wolpaw
1Helen Hayes Hospital, New York State Department of Health, Route 9W, West Haverstraw, New York 10993, USA. thompsona@helenhayeshosp.org
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.
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