Social Decision-Making in the Primate Brain

People are frequently forced to make decisions in social contexts, taking into account not only the social perceptual aspects of their environment, but also the effects of their actions; what will happen to themselves and what will happen to other individuals. These decisions involve consideration of potential outcomes and choosing what best suits the decision maker’s own needs, sometimes at a cost, and sometimes at a benefit, of others. Yet, the brain mechanisms that acquire and evaluate social information to subsequently form social decisions remain poorly understood. Thus, it is imperative to better understand the computations underlying social decision-making. Across three independent studies, I focus on the neural basis of making decisions in a social context. In the first study (Chapter 2), I used a relatively novel combination of restricted spatial independent component analysis and multiple regression techniques to demonstrate that distinct regions encode making decisions for other people, relative to making decisions for oneself. In the second study (Chapter 3), I investigated how large-scale functional networks shape behavior in social contexts, and examined how broad, goal-oriented networks couple with specific cortical sites to orchestrate social motivation. In my last study (Chapter 4), I examined the relationship between social perception and social decision-making at the single-neuron level in the monkey superior temporal sulcus, a region known for social perceptual processing. Here, I demonstrated that this classically social perceptual region additionally responds to social decision-making processes, and that neurons in this region multiplex both types of information. Collectively, this research points to specific regions in the brain that encode multiple aspects of social behavior and decision-making, and the interaction between perception and goal-oriented cognition process that drive complex social behavior. Lastly, this body of research also highlights the importance of examining the neural mechanisms of social behavior both at the larger systems and network levels, as well as at the single-neuron level.