SPIKE DISCHARGE REGULARITY OF VESTIBULAR NEURONS IN LABYRINTHECTOMIZED GUINEA-PIGS

Single unit activity of second-order vestibular neurons was recorded i n alert guinea pigs. Here, we compared the spike discharge regularity (measured by calculating the coefficient of variation (CV)) of neurons from control animals with those from animals labyrinthectomized 1 wee k before. The mean CV (+/-SD) were the same in both groups (0.72 +/- 0 .43 vs. 0.70 +/- 0.39). Furthermore, in both groups, the CV was relate d to the resting rate (RR) according to the same law (CV = 4/root RR). Because the discharge of a neuron is more regular when it is due to a pacemaker activity than when it is due to the synaptic drive. we conc lude that restoration in the firing rate after labyrinthectomy is due to increase in the synaptic drive rather than to increase in the (intr insic) pacemaker activity. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.