Title: Faces evoke social network information in amygdala and entorhinal cortex

Face perception is crucial for understanding social networks and maintaining social relationships. Here, we investigated how face stimuli evoke neural representations of social network information in amygdala and entorhinal cortex of macaque monkeys. To characterize social network knowledge for individual monkeys, we collected surveillance videos of their home, neighboring, and unfamiliar social groups at the Johns Hopkins breeding farm. Videos collected across a three-month time frame were analyzed for interactive and solitary behaviors in four stable social groups, ranging in size from 7–18 individuals. We used this behavioral data to construct multi-edge social network graphs for these groups based on dominance relationships, facial threat behavior, physical aggression, dominance mounting, stealing, submissive facial signals, physical submission, affiliative facial gestures, grooming, physical proximity, social play, and knowable genetic relationships. Two subject monkeys from the same group were studied with linear array probe recording in amygdala and entorhinal cortex while viewing photographs of monkeys from the home, neighboring, and unfamiliar groups. We analyzed neural coding of personal social knowledge about home and neighboring groups, using unfamiliar monkeys as a control for social information based solely on visual appearance. We found that many neurons in both amygdala and entorhinal cortex encode personal social knowledge about relationships involving the subject monkey, relationships involving other monkeys, and relationships across the entire groups (home and neighboring), including dominance hierarchies, physical and symbolic agonism, physical and symbolic affiliation, and the knowable tree of genetic relationships.