Change of the functional state of the peripheral neuromuscular apparatus during the formation of a dominant in the spinal cord

Summary

The authors studied changes of the functional state of the peripheral neuromuscular apparatus during elaboration of the spinal cord dominant. The dominant was built up in one of the flexor centers of the frog's hindleg through application of rhythmic subliminal stimuli. The formation of the dominant manifested itself by inversion of the reciprocal relations between the centers of antagonists. It was found that as the dominant appears in a flexor center of the spinal cord in a motor nerve and in the muscle innervated by it in the corresponding limb, rheiobase, chronaxie, the threshold quantity of electricity, and the threshold energy of the stimulating current decrease, with simultaneous increase of all these parameters in the contralateral extremity. Disappearance of the dominant is accompanied by restoration of the initial level of excitability of the nerve and muscle, while the transfer of the dominant from a flexor center in one extremity to the centers of the other extremity leads to corresponding modifications in their excitability.