The firing properties of second-order vestibular neurons in correlation with the far-field recorded vestibular-evoked response.

Action potentials of the second-order vestibular neurons of ten cats were recorded, both in rest and responding to sinusoidal and intense impulse acceleration stimuli. The data were compared with the far-field recorded vestibular-evoked response induced by the same impulse stimuli. It was found that the irregular (kinetic) neurons, which had a phase lead relative to head velocity, were capable of responding to these impulses with a latency as short as 3.5 msec after the start of head acceleration. It is assumed, therefore, that these neurons are the generators of the second wave of the vestibular-evoked response, having a similar latency. A high correlation was found between the latency of the first peak in the poststimulus time histogram in response to acceleration impulses and the phase of the response to sinusoidal rotations. The regular (tonic) vestibular neurons did not respond to acceleration impulses and probably did not contribute to the vestibular-evoked response.