EVOKED ACTIVITY OF SINGLE NEURONS IN SENSORY ASSOCIATION CORTEX OF THE CAT

Abstract

Unit activity in a sensory association area was studied in unrestrained, unanesthetized cats. The responses to visual and auditory stimuli were analyzed by means of a summing technique which provided information about the temporal pattern of response. The observed patterns of response fell into two distinct groups. In one of the groups the initial effect of the stimulus was an increase in the rate of the unit discharge. In the other group the initial effect of the stimulus was a decrease in unit activity. Visual stimuli were more effective in eliciting responses than were auditory stimuli, but responses to both types of stimuli were generally similar with respect to temporal patterns of response in the individual unit. There was a high degree of convergence of the inputs evoked by auditory and visual stimuli. The results suggest that association cortex units show less modality specificity and more interaction between modalities than do primary sensory units.