Figure 2.

Event-elicited signal change in VOI. Each VOI was a sphere 6 mm in diameter centered on the Talairach coordinates showing the highest event-related z statistic in a previous experiment using this paradigm (Knutson et al., 2003). These were the gain versus nongain anticipation contrast maxima in the left NAcc (-9, 10, 0; A) and right NAcc (11,12, 0; B) and the gain versus nongain outcome maxima in the mFC (1, 53, -6; C). Data were averaged across the VOI and extracted during the acquisition corresponding to the lagged peak of the event-related hemodynamic response in adolescents (squares) and adults (circles) and are expressed as percentage signal change from baseline, where baseline is mean signal value averaged across the entire time series. There was a main effect of incentive amount (from 0 to 5 dollars) on activation during anticipation of both gains and losses in the left and right NAcc, where a main effect of valence among the incentive-laden trials indicated greater anticipatory activation by potential gains compared with losses in both VOI. There was a significant age group times incentive amount interaction effect on anticipatory activation in the gain trial series in the right NAcc, with significantly (^*p < 0.05) lower signal increase while anticipating responding to win the large (5 dollars) gains in adolescents. In the mFC VOI, a significant valence by outcome interaction indicated that in gain trials (but not in loss-avoidance trials), notification of “hits” significantly increased signal relative to notification of “misses.” There were no significant main or interactive effects of age group on activation in the mFC VOI.