Early adolescence may be an important period for developing sensitivity to uncooperative behavior. With this functional magnetic resonance imaging study, we examined longitudinal changes in trusting behavior and their neural correlates in regions of interest (ROIs) selected a priori: the medial prefrontal cortex (mPFC), dorsal anterior cingulate cortex (dACC), left anterior insula (AI), bilateral ventral striatum, and right dorsal striatum. Participants played the investor in a Trust Game with

more »

... n uncooperative trustee (an anthropomorphic cartoon) three times, with one year between each wave. We preregistered our hypotheses and analytic plan. In total, 160 scan sessions of 77 participants (age at wave 1: M=13.89) were included in the analyses. First, we examined changes in trusting behavior involving an uncooperative other, and showed that participants' investments decreased with wave. Next, we examined whether the investment and repayment phase yielded enhanced activity in the ROIs. In each phase we observed increased activity in the mPFC, dACC, and dorsal striatum, but no effects were found in the bilateral ventral striatum (and AI did not reach significance after multiple comparisons correction). Finally, we examined whether ROI activity changed with wave. During the repayment phase, dorsal striatum activity increased with wave (although this finding did not survive Bonferroni correction, it closely approached our threshold for significance). Together, these results indicate that young adolescents become increasingly responsive to uncooperative behavior; that trust behavior robustly enhanced activity in brain regions previously related to trust and decision-making in social context; and increased involvement of dorsal striatum across early adolescence.