Pharmacological Inhibition of the Nucleus Accumbens Increases Dyadic Social Interaction in Macaques

Abstract

The nucleus accumbens (NAc) is a central component of the brain circuitry that mediates motivated behavior, including reward processing. Since the rewarding properties of social stimuli have a vital role in guiding behavior (both in humans and nonhuman animals), the nucleus accumbens is likely to contribute to the brain circuitry controlling social behavior. In rodents, prior studies have found that focal pharmacological inhibition of NAc and/or elevation of dopamine in NAc increases social interactions. However, the role of the NAc in social behavior in nonhuman primates remains unknown. We measured the social behavior of eight dyads of male macaques following (1) pharmacological inhibition of the nucleus accumbens using the GABAAagonist muscimol and (2) focal application of quinpirole, an agonist at the D2 family of dopamine receptors. Transient inhibition of the NAc with muscimol increased social behavior when drug was infused in submissive, but not dominant partners of the dyad. Focal application of quinpirole was without effect on social behavior when infused into the NAc of either dominant or submissive subjects. Our data demonstrate that the NAc contributes to social interactions in non-human primates.Significance statementA range of neuropsychiatric disorders present with altered reward processing and social behavior. The nucleus accumbens is a critical brain region for reward processing and motivated behavior. While prior studies in rodents have suggested a role for the nucleus accumbens in social behaviors, no studies have examined this role in the primate brain. Here, we bridge this gap and demonstrate that focal modulation of activity within the primate nucleus accumbens alters social behavior and that this effect is modulated by the social status of the infused animal.