CROSSED INHIBITION OF THE SOLEUS-H REFLEX DURING PASSIVE PEDALING MOVEMENT

We hypothesized that sensory input from the moving leg induces presyna ptic inhibition of the soleus H reflex pathway in the contralateral st ationary leg. The results showed a crossed inhibition during passive p edalling movement of the leg, which was not removed by low levels of t onic contraction of soleus in the stationary leg. The inhibition was c orrelated exponentially to the rate of the movement (R-2 = 0.934, P < 0.05) and was not dependent on the quadrants through which the moving leg was passing. Static flexion of the stationary leg caused ipsilater al inhibition of the reflexes (t = 5.590, P < 0.05), independent of th e orientations of the other leg. We concluded that sensory inflow from the moving leg induces presynaptic inhibition in the stationary leg, that a complex transformation of the sensory input in the spinal cord or brain underlies the tonic crossed inhibition and phasic ipsilateral inhibition, and that descending motor commands exert a powerful contr ol over these sensorimotor modulatory mechanisms. (C) 1998 Elsevier Sc ience B.V.