Stretch--induced inhibition of spontaneous EMG activity in extensor muscles of the rat caused by chronic deafferentation.

Stretching the chronically deafferented soleus muscle has recently been found to inhibit spontaneous EMG activity recorded by silicone-plate electrodes in this muscle. In order to ascertain whether this stretch-induced inhibition (SII) of EMG activity is not restricted exclusively to the soleus, a study was made of SII in the gastrocnemius muscle employing either concentric EMG needles or bipolar "fish-hook" electrodes. The results showed that SII of spontaneous EMG activity can be demonstrated in the soleus and gastrocnemius muscles (both extensor muscles) several days after dorsal rhizotomy L1-S1, employing all three modes of EMG recording in awake rats (namely, silicone-plate electrodes, concentric electrodes and bipolar "fish-hook" electrodes). It is suggested that ventral root afferents may be involved in this phenomenon.