Short Latency Vestibular Evoked Responses to Linear Acceleration Stimuli in Small Mammals: Masking Effects and Experimental Applications

Abstract

Different potential were recorded from a site close to the 8th nerve in chinchillas in response to linear acceleration pulses. Acoustic masking allowed us to distinguish between an early response (within 1 ms after initiation of the acceleration) of probable vestibular origin and later responses of probable cochlear origin. The latter were abolished by intense acoustic masking and by surgical ablation of the cochlea. The early potential was slightly reduced by simultaneous acoustic masking with white noise above 65 dB SPL and was most sensitive to 1 kHz narrow band masking. Vestibular neurons seem to be stimulated by high frequency movements of their hair cell cilia, and vestibular compound action potentials can be recorded as soon as a sufficient number of neurons are brought to a synchronized response. These vestibular evoked potentials may provide a tool for experimental studies on vestibular function in laboratory animals.

Key Words:

• evoked potentials
• chinchilla