BEHAVIOUR OF PRIMARY HORIZONTAL CANAL NEURONS IN ALERT AND ANESTHETIZED GUINEA PIGS

Abstract

The activity of the primary horizontal canal neurons was investigated in alert and anesthetized guinea pigs.The average resting rate in the alert guinea pigs was 47.3±21.2 spikes/sec. These values were significantly higer than those from anesthetized animals which had an average rate of 39.1 spikes/sec. In alert animals the average gain from a total of 66 units tested at 0.3Hz sinusoidal rotation was 0.42±0.37 spikes/sec/deg/sec and this value was not different from the results for anesthetized guinea pigs. The average phase lag for the angular acceleration was 57.3±20.7 degrees in alert guinea pigs, and this was significantly smaller than that for the anesthetized animals. The number of cutoff neurons at 0.3Hz was one out of 67 neurons in the alert guinea pigs and seven out of 64 neurons in the anesthetized guinea pigs. The vestibular efferent system is most likely to be responsible for these different results from alert vs anesthetized guinea pigs. This system appears to help control the generation of functional distortion of the semicircular canal endorgans, when mechanical stimulation is trasformed to neural activities.