Reciprocal cooperation is a hallmark of social groups and is central to successful social interaction, playing a major role in evolutionarily shaping brain functions and enabling rich social interactions. This remarkable ability is frequently disrupted in neurodevelopmental and psychiatric conditions with mild to severe social challenges, including in autism spectrum disorder (ASD). Individuals with ASD frequently show difficulties in their ability to reciprocally cooperate with others and have tendencies to employ less flexible and more laborious strategies.

Discovering if and how people can causally promote reciprocal cooperation can facilitate translational efforts. However, investigating the neural mechanisms of reciprocal cooperation has been challenging. This is largely due to the fact that some lab animal models of neuroscience do not reliably exhibit cooperative behaviors, let alone reciprocity. Therefore, there is a need to study these neural mechanisms in a species whose social structures strongly depend on reciprocal cooperation. The common marmoset is one such species well-known for their prosociality and high social tolerance among group members for promoting and maintaining cooperative behaviors. Furthermore, their evolutionary similarity and brain architecture homology to humans provide a higher translational value than other lab animal species.

In this proposal spanning interdisciplinary expertise, Steve Chang, Anirvan Nandy and Monika Jadi plan to capitalize on recent advances in video-based tracking of complex behaviors using deep learning networks to rigorously catalog ongoing behaviors of cooperating marmoset dyads. The team then aims to apply the tracking of social head gaze behaviors of pairs of marmosets concurrently with wireless, high-density, neural techniques to investigate the neural underpinnings of cooperative interactions. They aim to examine neural activity from the orbitofrontal cortex (OFC) based on the evidence from human neuroimaging during simplified cooperative interaction games, supporting the role of OFC in processing the rewarding aspects of mutual and reciprocal cooperation. Specifically, they will determine the fundamental dependencies of neural activity across mutual and altruistic cooperation, and successful versus unsuccessful outcomes. Crucially, the researchers will apply specific microstimulation protocols in the OFC, known to either promote or disrupt reward functions, to directly test if and how marmosets can promote or suppress reciprocal cooperation. In doing so, they will use computational modelling to determine a set of dynamic behavioral dependencies that are altered by different stimulation conditions to provide novel mechanistic insights into how brain stimulations can lead to changes in reciprocal cooperation.

Findings from these studies are expected to determine the effects of causal brain stimulation with precise, naturalistic, behavioral data, and facilitate future translational efforts in leveraging brain stimulations to promote reciprocal social interactions in individuals with ASD.