Types of Neuronal Activity in the Lateral Vestibular Nucleus

Abstract

A study of the responses of 150 single neurons in the lateral vestibular nucleus to a constant horizontal angular acceleration and deceleration of 4°/sec² for 50 sec revealed that 44% of those found did not respond to stimulation. These were termed type V neurons and may represent projections onto the lateral vestibular nucleus from the otolith organs, from the spinal cord, from unstimulated semicircular ducts, or from some non-vestibular system. Type I (30.7%) and type II (20.7%) neurons in the lateral vestibular nucleus appear to be the third-order neurons which are activated by deflection of the cupula and connected with receptors in the semicircular ducts via internuncial second-order neurons connecting the vestibular nuclei, or neurons relaying through the cerebellum. There are fewer type III and type IV neurons (those likely related to sensory integration) in the lateral vestibular nucleus than in the medial vestibular nucleus. The average resting frequency of type V neurons is higher than that of other types of neurons, and the average resting frequency of neurons in the lateral vestibular nucleus is also higher than in the medial vestibular nucleus.