Pinpointing the cerebellum's contribution to social reward processing

Abstract

Although the cerebellum has been traditionally thought of as a motor processing brain region, recent evidence suggests that the cerebellum is functionally diverse. The posterior cerebellum in particular has been shown to play a role in social cognitive processes, and recent work has proposed that this region helps fine tune mental models of social cognition to, for example, to ensure accurate selection of actions in a social scenario. Social interactions with strangers are difficult, in part because we are constantly trying to gauge whether the other person likes or dislikes us without much information for our mental models to help us. From a reward processing standpoint, this requires tracking the value (positive or negative) of people’s valence to us and ensuring that our predictions about people’s affect towards us are correct. The aim of this project was to specify how the posterior cerebellum uniquely contributes to social reward processing, and to distinguish this contribution from regions that are canonically part of the reward and social brain regions. Participants, ages 12-36, completed a well-matched social and monetary reward task in the scanner. In the monetary condition, participants were asked to select which of two doors would result in winning money, and in other trials losing money. In the social condition, participants were asked to select which of two faces representing people would like or dislike them. Representational similarity analysis was used to compare the responses of reward and social brain regions to conditions in which participants either won or lost money and were either liked or disliked by others. We found that portions of the posterior cerebellum were sensitive to social reward, and treated positive social rewards more similarly to negative social rewards than the striatum. These results suggest that these regions in the posterior cerebellum has a dissociable contribution to social reward processing compared to other brain regions.