[The responses of frog vestibular neurons to the combined temperature microstimulation of the semicircular canals]

Abstract

Controlled temperature microstimulation of the frog semicircular canal (heating of 2 sec duration, peak amplitude from 0.5 to 5.0 degrees C above the temperature level of the labyrinth, 17-19 degrees C) may be considered as an analogue of angular acceleration in the plane of the canal. Combined temperature microstimulation of some canals may be considered as a physical model of complicated space rotations. Responses of the frog vestibular nuclei's neurons (n = 278) to temperature microstimulation showed that 80% of them had inputs from 1-2 canals and only 20% of neurons--from 3-6 canals. 201 neurons (72.3%) had ipsilateral inputs only; 14 neurons (5%)--contralateral ones only; 63 neurons (22.7%) had both inputs. The most effective excitatory inputs were ipsilateral horizontal, ipsilateral posterior and contralateral posterior canals; the least effective were contralateral horizontal and contralateral anterior canals. Latent canal inputs (excitatory as well as inhibitory) seem to exist as revealed in combination with the effective inputs.