Developmental differences in posterior mesofrontal cortex recruitment by risky rewards.
Might increased risk taking in adolescence result in part from underdeveloped conflict-monitoring circuitry in the posterior mesofrontal cortex (PMC)? Adults and adolescents underwent functional magnetic resonance imaging during a monetary game of "chicken." As subjects watched ostensible winnings increase over time, they decided when to press a button to bank their winnings, knowing that if they did not stop pursuing money reward before a secret varying time limit, they would "bust" and either lose the money accrued on the current trial (low-penalty trials) or forfeit trial winnings plus a portion of previous winnings (high-penalty trials). Reward accrual at risk of low penalty (contrasted with guaranteed reward) activated the PMC in adults but not in adolescents. Across all subjects, this activation (1) correlated positively with age but negatively with risk exposure and (2) was greater when subjects busted on the previous low-penalty trial. Reward accrual at risk of high penalty was terminated sooner and recruited the PMC in both adults and adolescents when contrasted with guaranteed reward. Predecision PMC activation in the high-penalty trials was significantly reduced in trials when subjects busted. These data suggest that (1) under threat of an explicit severe penalty, recruitment of the PMC is similar in adolescents and adults and correlates with error avoidance, and (2) when potential penalties for a rewarding behavior are mild enough to encourage some risk taking, predecision PMC activation by a reward/risk conflict is sensitive to previous error outcomes, predictive of risk-aversive behavior in that trial, and underactive in adolescents.