[Effect of unilateral trauma of the sciatic nerve on characteristics of motor and reflex responses of paired gastrocnemius muscles].

The influence of unilateral n. ischiadicus lesion of conductivity on the electromyographic characteristics of the rat gastrocnemius muscles was investigated. The lesion was made by n.

[Response of motor units of the abdominal musculus rectus to afferent input in the course of the long-lasting activity in rats].

In rats, in the course of a long-lasting m. rectus abdominis motor units activity combined with repetitive afferent stimulation of the ischiadic nerve, the units' firing rate decreased. The dependence of the motor units response to afferent stimulation on the background firing rate was preserved during the long-lasting activity in spite of changes in the background firing rate.

[Effect of the sciatic nerve blockade on the function of the contralateral motor center in the rat gastrocnemius muscle].

When the rat spinal motor centre was activated by fixing the animal in a supine posture, the motor units of intact gastrocnemius muscle fired more frequently in the high-frequency range. Under conditions of the ischiatic nerve blockade, a shift to an increase in the background firing frequency of the motor units related to intact gastrocnemius muscle seems to be related to increased motoneurone excitability occurring because of the contralateral denervation.

Responses of constantly firing motor units to afferent stimulation.

Constantly firing motor units of the short abductor muscles of the first finger in the human hand and the abdominal wall muscle in immobilized rats responded to afferent stimulation of the median and sciatic nerves respectively with changes in the nature of spike activity. In the first 250 msec of the post-stimulus period, the frequency of motor unit spike activity became unstable and peri-stimulus histograms were individually quite distinct. This was followed by relative stabilization of motor unit discharge frequencies, and the subsequently (750 msec) determined motor unit spike frequency depended on most cases on the background spike frequency.