[Influence of a tendon reflex on the motor neurons of antagonistic muscles in man].

The knee reflex was evoked during rhythmic activity of relatively low-threshold motor units of m. biceps fem. activated by weak voluntary contraction. Along with a reflectory response from m. rectus fem. the discharges from impulsating units of m. biceps fem. synchronous to the response were observed, as well as the recruitment of new units. Post-stimulation histograms and statistical analysis of interspike intervals of m. biceps fem. units revealed in most units a noticeable excitatory effect syndhronous to a reflectory response from m. rectus fem. This may be accounted fro by the presence of excitatory inputs of Ia afferents on motoneurons of the antagonist. Some delayed inhibitory effects on the antagonist motoneurons were found to follow their synchronous excitation. Apparently, they are analogous to the "silent period" of the antagonist motoneurons during the evoked tendon reflex.