Effect of sensory stimuli on single unit activity in the posterior hypothalamus

Abstract

The effects of sciatic, acoustic and photic stimuli on 147 units in the posterior hypothalamic nucleus of the anesthetized cat were statistically evaluated for their influences on the rate and pattern of firing. The mean spontaneous firing rate of these units is low, i.e., 0.54 spikes/sec, with 68%, 73.5% and 76.8% of the cells responding to photic, acoustic and sciatic stimuli, respectively, with various degrees of facilitation or inhibition. Histograms drawn for these units have shown both early and long latency responses with double or triple peaks. In 105 cells convergence was found, with more than half of the units responding to all three modalities. These results demonstrate, at the single cell level, the existence of somato-sensory, visual and acoustic projections to the posterior hypothalamus, which may modify its various autonomic functions.