Social exclusion and punishment of excluders: neural correlates and developmental trajectories

Social exclusion is a distressing experience and can result in a reduction of prosocial behavior. In this fMRI study we examined the neural networks involved in social exclusion and subsequent fairness considerations across adolescent development. Participants from 3 age groups (10-12, 14-16 and 19-21 year olds) participated in the study and performed two tasks; first, participants played Cyberball to induce feelings of social inclusion and exclusion, followed by a Dictator game in which participants were asked to divide coins between themselves and the players who previously included or excluded them. Results revealed a network of regions associated with social exclusion, which involve the medial prefrontal cortex (mPFC)/ventral anterior cingulate cortex (vACC), subgenual ACC and the lateral PFC, as well as the insula and the dorsal ACC. Although social exclusion generated strong distress for all age groups, 10-12 year olds showed increased activity in the subgenual ACC in the exclusion game, which has been associated in previous studies with negative affective processing. Results of the Dictator game revealed that all age groups selectively punished the excluders by making lower offers. These offers were associated with activation in the temporoparietal junction (TPJ), superior temporal sulcus (STS) and the lateral PFC. Age comparisons revealed that adults showed additional activity in the insula and dorsal ACC when making offers to the excluders. The results are discussed in the light of recent findings on neural networks involved in social exclusion and the development of social brain regions.