Two functions of the primate amygdala in social gaze

Prefrontal-Amygdala Pathways for Object and Social Value Representation

This special focus article was prepared to honor the memory of our National Institutes of Health colleague, friend, and mentor Leslie G. Ungerleider, who passed away in December 2020, and is based on a presentation given at a symposium held in her honor at the National Institutes of Health in September 2022. In this article, we describe an extension of Leslie Ungerleider's influential work on the object analyzer pathway in which the inferior temporal visual cortex interacts with the amygdala, and then discuss a broader role for the amygdala in stimulus-outcome associative learning in humans and nonhuman primates. We summarize extant data from our and others' laboratories regarding two distinct frontal-amygdala circuits that subserve nonsocial and social valuation processes. Both neuropsychological and neurophysiological data suggest a role for the OFC in nonsocial valuation and the ACC in social valuation. More recent evidence supports the possibility that the amygdala functions in conjunction with these frontal regions to subserve these distinct, complex valuation processes. We emphasize the dynamic nature of valuation processes and advocate for additional research on amygdala-frontal interactions in these domains.

Widespread implementations of interactive social gaze neurons in the primate prefrontal-amygdala networks

Social gaze interaction powerfully shapes interpersonal communication. However, compared with social perception, very little is known about the neuronal underpinnings of real-life social gaze interaction. Here, we studied a large number of neurons spanning four regions in primate prefrontal-amygdala networks and demonstrate robust single-cell foundations of interactive social gaze in the orbitofrontal, dorsomedial prefrontal, and anterior cingulate cortices, in addition to the amygdala. Many neurons in these areas exhibited high temporal heterogeneity for social discriminability, with a selectivity bias for looking at a conspecific compared with an object. Notably, a large proportion of neurons in each brain region parametrically tracked the gaze of self or other, providing substrates for social gaze monitoring. Furthermore, several neurons displayed selective encoding of mutual eye contact in an agent-specific manner. These findings provide evidence of widespread implementations of interactive social gaze neurons in the primate prefrontal-amygdala networks during social gaze interaction.