SOLEUS H-REFLEX MODULATION AND PAIRED REFLEX DEPRESSION FROM PRONE TO STANDING AND FROM STANDING TO WALKING

Abstract

Patterns of soleus H-reflex modulation as a function of posture, task, and reflex activation history were assessed with three experimental paradigms: lying prone compared with standing unsupported; standing compared with the initiation of walking; and standing compared with the mid stance phase of walking. Paired H-reflexes, 80 ms apart, were evoked under each condition. The paired reflex depression (PRD), the percentage depression of the second H-reflex relative to the first H-reflex, was modulated independently of the first H-reflex across the postures and tasks. These results reveal divergent patterns of segmental reflex modulation and support the idea that segmental reflexes are controlled by multiple mechanisms.

Keywords:

• gait
• homosynaptic depression
• H-reflex
• paired reflex depression
• presynaptic inhibition