Afferent and efferent connections of cat omnipause neurons

Afferent and efferent connections of behaviorally identified omnipause neurons involved in saccadic eye movements were investigated electrophysiologically in cats anesthetized with ketamine hydrochloride. Pause cells were polysynaptically excited by electrical stimulation of the optic chiasm (mean latency = 8.3 ms), the visual cortex (mean latency = 7.3 ms), and the superior colliculus (mean latency = 2.6 ms). Bilateral removal of either the visual cortex or the superior colliculus 1 week prior to the experiment abolished optic chiasm responses. Pause cells were antidromically activated by electrical stimulation of the prerubral fields (mean latency = 1.1 ms), or the pontine and medullary reticular formation (mean latency = 1.0 ms). Frequently, the same pause cell was antidromically excited by prerubral and pontine or medullary reticular stimulation indicating that its axon was branched. The spontaneous discharge of pause cells was polysynaptically suppressed by sustained galvanic polarization of either labyrinth, or by multiple shock stimulation in the reticular formation.