  Individuals react differently to social experiences; for example, people who
are more sensitive to negative social experiences, such as being excluded, may
be more likely to adapt their behavior to fit in with others. We examined
whether functional brain connectivity during social exclusion in the fMRI
scanner can be used to predict subsequent conformity to peer norms. Adolescent
males (N = 57) completed a two-part study on teen driving risk: a social
exclusion task (Cyberball) during an fMRI session and a subsequent driving
simulator session in which they drove alone and in the presence of a peer who
expressed risk-averse or risk-accepting driving norms. We computed the
difference in functional connectivity between social exclusion and social
inclusion from each node in the brain to nodes in two brain networks, one
previously associated with mentalizing (medial prefrontal cortex,
temporoparietal junction, precuneus, temporal poles) and another with social
pain (anterior cingulate cortex, anterior insula). Using cross-validated
machine learning, this measure of global network connectivity during exclusion
predicts the extent of conformity to peer pressure during driving in the
subsequent experimental session. These findings extend our understanding of how
global neural dynamics guide social behavior, revealing functional network
activity that captures individual differences.
