CORD POTENTIALS IN THE SPINAL CAT

Abstract

Potentials were recorded from the dorsal surface of the cord synchronously with reflex responses myographically recorded in acute and chronic spinal cats. Crossed inhibition of the ipsilateral flexor reflex is associated with an approximately proportional reduction of the 1st negative crest of the internuncial complex. This inhibition is roughly proportional to the depth of positivity obtaining at the time of the ipsilateral volley. Hence the principal site of this inhibition is internuncial. Even at stimulation intervals at which the negative complex is little reduced, the positive wave due to the ipsilateral volley is usually obliterated and even the residual positivity from the contralateral volley is frequently reduced. Synchronous spatial reflex facilitation is associated with facilitation of the negative internuncial complex. Temporal reflex facilitation is associated with reduction of the negative internuncial potential from the second volley. These results are tentatively interpreted upon the assumption that negative and positive cell potentials contribute to the electrical changes recorded.