Effect of passive stepping on the H-reflex in the wrist flexor

摘要

It is possible for patients with spinal cord injury and stroke to regain locomotor-like activity with intense step training on a treadmill. However, the neural mechanisms underlying the reattainment of locomotor activity are unknown. In particular, the principles governing interlimb coordination is not known. Therefore, we investigated modulation of the H-reflex in the flexor carpi radialis (FCR) of 10 subjects during passive stepping of the leg. Passive stepping tasks were performed with the aid of a robotic gait trainer system (Loko-mat). The H-reflex in the FCR was elicited by electrical stimulation of the median nerve at the elbow level and recorded during 10 different phases of the walking cycle and static standing condition. The results showed that passive stepping significantly suppresses the FCR H-reflex amplitude as compared with static standing condition. These results suggest that movement-related afferent leg feedback mediates suppression of forearm H-reflex during passive stepping.