Nucleus accumbens single-unit activity in freely behaving male rats during approach to novel and non-novel estrus.

To assess the role of nucleus accumbens (NAcc) during approach to novel sexually arousing stimuli, we evaluated NAcc single-unit activity in male rats during the presentation of vaginal estrus extracted from novel and familiar female rats. After control stimulus presentations, animals were exposed to two estrous presentations from a female in the same or separate colony. A significantly larger proportion of units increased firing rate in the novel (11/32; 34%) than the familiar condition (2/28; 7%) during approach to the first but not the second presentation. Response magnitudes to novel but not familiar estrus were also greater than those during control trials. Collectively, these results provide further evidence of a role for the NAcc in the processing of novel sexually arousing information.