Acoustical Vestibular Stimulation in the Guinea Pig: Vestibular Nerve Response

Abstract

Responses from single vestibular nerve cells were elicited by slow time-varying pressure changes in the external auditory meatus. The resting discharge from these cells was regular and rapid (80–160 pulses/sec). Stimulation generally produced a reduction of discharge rate for those cells that could be acoustically activated (approximately 40%). Minimum stimulus intensities required to elicit clear responses were 1–2 cm Hg and response latencies ranged from 1 to 3 sec. The decay in discharge rate appears exponential with a time constant in the area of 2 sec. Data from the present study correlate well with previously reported observations on head and eye movements elicited by acoustical stimulation. Minimum stimulus intensities required to demonstrate head and eye movements were approximately 2 cm Hg and response latencies ranged from 2 to 8 sec. The observations obtained to date strongly support the hypothesis that acoustical stimulation may activate vestibular receptors. Moreover, these data suggest that the mechanism of stimulation may involve a slow flow of fluid through the membranous labyrinth. [Research supported by Aerospace Medical Research Laboratories, USAF.]