Neural dynamics of reward processing in naturalistic settings

The brain’s reward system—which helps people learn which decisions proved valuable and worth repeating—is hypothesized to play a central role in how individuals form connections with others. Conversation is a primary way that people interact, and thus an ideal context for studying how these connections form and endure. When conversations feel rewarding, people become more motivated to interact further, creating opportunities to develop strong connections that produce even more rewarding interactions. This project tests this hypothesis by investigating the biological processes in the brain that make naturalistic conversations rewarding, and how these processes both shape and are shaped by interactions with other people. Quantifying these neural mechanisms could provide a foundation for mechanistically grounded prevention and intervention strategies for depression, anxiety, and suicide that have the potential to reduce the individual, economic, and social burden of mental illness. Additionally, findings from this work have the potential to inform educational, workplace, community, and technological contexts in which engaging in interactions, joint decision-making, and problem-solving are essential, as well as the design of interactive technologies that aim to support or emulate such interactions. This project leverages fMRI hyperscanning, which is the simultaneous recording of brain activity from two interacting individuals, to capture whole-brain reward-related activity while individuals engage in conversation. Aim 1 tests the hypothesis that the experienced value of conversations, and therefore the decision to continue to engage in them, is shaped not only by the individual reward response but also by the amplification and coordination of affective and neural states between the conversation partners. Aim 2 tests the hypothesis that these coordinated brain dynamics reflect and predict longer-term, real-world social connection, as well as momentary rewards. The project recruits pairs of people with and without existing social connections to engage in naturalistic conversations on topics of varying mutual interest while undergoing fMRI hyperscanning. This method thus enables an unprecedented and more comprehensive account of the underlying neurobiological mechanisms that underlie social connection, characterized by both established individual reward processes and novel coordinated reward signals which are shaped by partners’ interdependent affective and neural states. In doing so, this project represents a paradigm shift in the study of social reward as dynamic and reciprocal with the goal of a better understanding of the foundational mechanisms of connection, which have implications for depression, anxiety, and suicide prevention. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.