Tyree, T. | bioRxiv Science

bioRxiv2025

Primate ACC encodes natural vocal interactions in a cocktail party

The Cocktail Party Problem (CPP)--extracting meaningful signals amid competing voices--remains poorly understood at the neural level, particularly in real-world contexts where it emerges naturally. We investigated the role of the anterior cingulate cortex (ACC), a structure implicated in social monitoring but rarely examined in relation to audition, to resolve the CPP in freely-moving marmoset monkeys engaged in ecological vocal exchanges. Analyses revealed that ACC is seemingly integral to resolving the CPP. Not only did neurons encode the calls of either the conversational partner or background callers, but this selectivity persisted even with overlapping background sounds, a hallmark of the CPP. Moreover, ACC activity reflected the conversational dynamics by encoding turn-taking structure, highlighting the importance of CPP resolution for navigating social interactions in complex natural soundscapes.

neuroscience↗

bioRxiv2022

Cross-Modal Representation of Identity in Primate Hippocampus

Faces and voices are the dominant social signals used to recognize individuals amongst human and nonhuman primates (1-4). Yet it is not known how these critical signals are integrated into a cross-modal representation of individual identity in the primate brain. Here we show that while, like humans (5-7), single neurons in the marmoset hippocampus exhibit selective responses when presented with the face or voice of a specific individual conspecific, a parallel mechanism for representing the cross-modal identities for multiple individuals is evident within single neurons and at a population level. Manifold projections likewise showed separability of individuals, as well as clustering for others families, suggesting that multiple learned social categories are encoded as related dimensions of identity in hippocampus. These findings demonstrate that neural representations of identity in hippocampus are both modality-independent and reflect the hierarchical structure of the primate social network. One-Sentence SummaryWe show that cross-modal representations of identity in primate hippocampus can be achieved by at least two distinct neural mechanisms and comprise multiple social categories that reflect different relationships.

neuroscience↗