The galvanically-induced vestibulo-ocular reflex in the cat.

Rotatory vestibular input is processed by receptor organs and relayed along the vestibular nerves to a central processor, whence the vestibulo-ocular reflex (VOR) is generated. Electrical stimuli applied to the labyrinth can bypass receptors and stimulate the nerve directly, thereby generating horizontal eye movements (EVOR). It was our purpose to mathematically relate the EVOR to the VOR in an effort to generate a parameter by which the experimental effects of ototoxins on the inner ear can be evaluated. A feline preparation was created in which the VOR and EVOR were measured in response to various sinusoidal stimuli. A detailed comparison between VOR and EVOR with respect to gain and phase was performed. From analysis of the data, the differential sensitivity to rotatory amplitude with respect to electrical amplitude was proposed as this parameter.