Brain structure and function and social exclusion reactivity in the Cyberball game.

Social exclusion or rejection is a universal stressor, and strong responses to rejection have been related to mental health issues. Previous studies linked rejection to concurrent brain activity in, amongst others, the insula or cingulo-operculum, areas related to pain processing. To date however, studies have only studied to the state of the brain during rejection, and not rejection in relation more stable brain characteristics. Identifying which brain areas are different among those that respond more to rejection could help us understand more of the biological underpinnings of rejection sensitivity and ultimately alleviate associated mental health issues. Here the relation between brain structure, resting-state functional connectivity and rejection reactivity outside of the MRI scanner was studied, in a multi-ethnic population-based sample of 1814 9-to-12-year-olds. Using the Cyberball paradigm, observed emotional facial expressions and self-reported feelings during peer rejection were measured. Stronger resting-state functional connectivity between the dorsal striatum, visual, and sensori-motor networks, and between the cingulo-operculum and dorsal attention network was related to negative emotional facial expressions during peer rejection (beta = 0.11-0.12). No associations were detected for self-reported reactions or brain structure. The dorsal striatum is related to automated behavior and functional connectivity between these and other networks may indicate why some children are more expressive in their reaction to rejection. Findings in the cingulo-operculum and dorsal attention network are in line with earlier studies, here suggesting that brain activity during rest is related to the risk of feeling 'hurt' when socially rejected.