Anterior cingulate cortex neurons in macaques encode social image identities

Abstract

The anterior cingulate cortex gyrus (ACCg) has been implicated in prosocial behaviors involving complex reasoning about social cues. While this indicates that the ACCg is involved in social behavior, it remains unclear whether ACCg neurons also encode social information during goal-directed actions without social consequences. To address this, we assessed how social information is processed by ACCg neurons in a reward localization task. Two rhesus monkeys performed the task using either social or nonsocial visual guides to locate rewarding targets. We found that monkeys can use both sets of guides, and many neurons in the ACCg distinguished social from nonsocial trials. Yet, this encoding was no more common in ACCg than in the prearcuate cortex (PAC), which has not been strongly linked to social behavior. However, unlike PAC, ACCg neurons were more likely to encode the unique identity of social visual guides compared to nonsocial, even though identity was irrelevant to the reward localization task. This suggests that ACCg neurons are uniquely sensitive to social information that differentiates individuals, which may underlie its role in complex social reasoning.