Trust plays an important role during adolescence for developing social relations. Although prior developmental studies give us insight into adolescents' development of differentiation between close (e.g., friends) and unknown (e.g., unknown peers) targets in trust choices, less is known about the development of trust to societal targets (e.g., members of a community organization) and its underlying neural mechanisms. Using a modified version of the Trust Game, our preregistered fMRI study examined the underlying neural mechanisms of trust to close (friend), societal (community member), and unknown others (unknown peer) during adolescence in 106 participants (aged 12–23 years). Adolescents showed most trust to friends, less trust to community members, and the least trust to unknown peers. Neural results show that target differentiation in adolescents' trust behavior is associated with activity in social brain regions implicated during mentalizing, reward processing, and cognitive control. Recruitment of the medial prefrontal cortex (mPFC) and OFC was higher for closer targets (i.e., friend and community member). For the mPFC, this effect was most pronounced during no trust choices. Trust to friends was additionally associated with increased activity in the precuneus and bilateral temporal parietal junction. In contrast, bilateral dorsolateral prefrontal cortex and anterior cingulate cortex were most active for trust to unknown peers. The mPFC showed increased activity with age and consistent relations with individual differences in feeling needed/useful.

Prosocial behavior during adolescence becomes more differentiated based on the recipient of the action as well as the perceived value or benefit, relative to the cost to self, for the recipients. The current study investigated how functional connectivity of corticostriatal networks tracked the value of prosocial decisions as a function of target recipient (caregiver, friend, stranger) and age of the giver, and how they related to giving behavior. Two hundred sixty-one adolescents (9–15 and 19–20 years of age) completed a decision-making task in which they could give money to caregivers, friends, and strangers while undergoing fMRI. Results indicated that adolescents were more likely to give to others as the value of the prosocial decision (i.e., the difference between the benefit to other relative to the cost to self) increased; this effect was stronger for known (caregiver and friends) than unknown targets, and increased with age. Functional connectivity between the nucleus accumbens (NAcc) and OFC increased as the value of the prosocial decisions decreased for strangers, but not for known others, irrespective of choice. This differentiated NAcc-OFC functional connectivity during decision-making as a function of value and target also increased with age. Furthermore, regardless of age, individuals who evinced greater value-related NAcc-OFC functional connectivity when considering giving to strangers relative to known others showed smaller differentiated rates of giving between targets. These findings highlight the role of corticostriatal development in supporting the increasing complexity of prosocial development across adolescence.

Discordant development of brain regions responsible for cognitive control and reward processing may render adolescents susceptible to risk taking. Identifying ways to reduce this neural imbalance during adolescence can have important implications for risk taking and associated health outcomes. Accordingly, we sought to examine how a key family relationship—family obligation—can reduce this vulnerability. Forty-eight adolescents underwent an fMRI scan during which they completed a risk-taking and cognitive control task. Results suggest that adolescents with greater family obligation values show decreased activation in the ventral striatum when receiving monetary rewards and increased dorsolateral PFC activation during behavioral inhibition. Reduced ventral striatum activation correlated with less real-life risk-taking behavior and enhanced dorsolateral PFC activation correlated with better decision-making skills. Thus, family obligation may decrease reward sensitivity and enhance cognitive control, thereby reducing risk-taking behaviors.