RESPONSES OF GUINEA-PIG PRIMARY VESTIBULAR NEURONS TO CLICKS

Responses of single neurons in the vestibular nerve to high-intensity clicks were studied by extracellular recording in anaesthetised guinea pigs. One hundred and two neurons in the posterior division of the su perior branch or in the inferior branch of the vestibular nerve were a ctivated at short latency by intense clicks. The latency of activation was short (median 0.9 ms) and the threshold was high: the click inten sity for evoking the response of these cells was around 60 dB above th e auditory brainstem response threshold. Animals were tilted and rotat ed to identify physiologically the sensory region of the labyrinth fro m which the activated neurons originated. Seventeen neurons responded to static tilt as well as clicks. These results show that vestibular r eceptors, probably the otoliths, respond to clicks at intensities corr esponding to those used in a new clinical test of the vestibulo-collic pathway.