Electrophysiological relations between the superior colliculus and the red nucleus in the cat.

Abstract

The electrical activity of single units located in the parvicellular part of the red nucleus (pRP) was recorded extracellularly in nitrous oxide anesthetized and C1-transected adult cats. In this area, neurons were found to respond to electrical stimulation applied to intermediate and deep layers of the right superior colliculus (SC). Forty neurons located in the pRN of both sides were studied. Three neurons out of 18 (16.6%) located in the contralateral pRN and six neurons out of 22 (27.3%) located in the ipsilateral pRN were driven by the right SC stimulation. The pRN neurons were separated into four groups according to the latency response to the SC stimulation: 1) 0.6-1.9 ms, 2) 2-4 ms, 3) 4-6 ms, 4) variable latency responses. Each of these four groups of neurons showed a particular pattern of discharge, even though their discharge frequency showed a strong consistency. Four pRN neurons, which responded to SC stimulation, showed a significant correlation with spontaneous horizonta