The effects of recurrent inhibition on the cross-correlated firing patterns of motoneurones (and their relation to signal transmission in the spinal cord-muscle channel)

摘要

Cross-correlation histograms (CCH) were computed for discharge sequences of pairs of motoneurones which were excited by sinusoidal muscle stretches. These CCH's were compared before and after opening of the recurrent inhibitory loop by Renshaw cell blocking agents. Periodic patterns in the CCH's indicative of specifically timed phase relations between discharges of different motoneurones were enhanced after Renshaw cell blockage. This was confirmed by power spectra computed for the CCH's. They contained power peaks about 50Hz which tended to increase after depression of recurrent inhibition. The correlation was thus due predominantly to line current interference which seemed to act as a common entrainment input at the spinal level. It is concluded that Renshaw cells de-correlate discharge patterns of different motoneurones of the same pool by injecting uncorrelated signals into them. This de-correlation is an important prerequisite for distortion suppression of signal transmission in a multi-channel system, like that of stretch reflex, and for its linearization.