Electrophysiological responses of nucleus accumbens neurons to novelty stimuli and exploratory behavior in the awake, unrestrained rat.

To establish a physiological correlate of goal-directed and reward-seeking non-operant behaviors, we studied the electrophysiological activity of NAcc neurons in unrestrained, naive Sprague-Dawley rats. Our results showed an inhibitory response in 21% (7/34) of the recorded NAcc neurons during spontaneous nosepoking behavior and in 16% (4/25) of the NAcc neurons when rats were fed with a favorite novel food morsel (popcorn). These data suggest that a subgroup of NAcc neurons is actively modulated during motivated behavior and during consummatory events resulting in a suppression of neuronal activity.