Compositionality of social gaze in the prefrontal-amygdala circuits

Social gaze underpins flexible primate communication and can be decomposed into three primitives: gaze content, social state, and gaze duration. To reduce dimensionality and facilitate generalization, the brain needs to represent these primitives in an abstract format. We show that social gaze is governed by a compositional code in the brain. During social gaze interactions in male and female macaques (neural recordings in two males), gaze exchanges were determined by how these primitives were combined, providing evidence for behavioral compositionality. The basolateral amygdala and the anterior cingulate gyrus represented content and state in abstract and orthogonal formats, whereas the dorsomedial prefrontal and orbitofrontal cortices exhibited limited generalization. Linear mixed-selective neurons facilitated this abstraction underlying generalization. Moreover, distinct channels routed content and state information through prefrontal-amygdala circuits, minimizing interference via linear mixed-selective neurons. These findings identify a neural grammar for social gaze, revealing compositional computations underlying flexible social communication.