Friend versus foe: Neural networks of prosocial decision-making with peers

Adolescents spend the majority of their time with their peer. Peers, and friends in particular, are known to play a salient role in adolescents' social decisions. Adolescents can act in more prosocial or selfish ways depending on who their interaction partner is. In the current study we aimed to examine prosocial behavior and its neural correlates in interactions with peers. Participants (N = 50, Mean age = 14 years) took part in a functional magnetic resonance imaging study where they were asked to make decisions regarding distributions of coins in three economic exchange paradigms. Participants made decisions for four different groups of peers: liked (i.e., friends), disliked classmates, neutral classmates, and unfamiliar peers. In line with expectations, participants were more prosocial towards friends and more selfish towards disliked peers than towards neutral and unfamiliar peers. Decisions for friends were associated with heightened activation in the ventromedial prefrontal cortex (vmPFC) and temporoparietal junction (TPJ); prosocial decisions for friends were specifically associated with heightened activation in putamen and the superior temporal sulcus (STS). These findings suggest that, possibly, mentalizing processes and value estimations of the relationship might underlie decisions involving friends. Decisions for disliked peers did not show significant heightened brain activation. These findings will open pathways to better understand the underlying processes of prosocial behavior in adolescence