and adult age groups both contained certain animals that displayed evidence of sign-tracking, adolescents overall showed significantly weaker sign-tracking than their adult counterparts (see Fig. 1). This adolescent-associated reduction in sign-tracking behavior is also evident in female rats (Doremus-Fitzwater & Spear, 2008; Doremus-Fitzwater & Spear, under revision) and has been confirmed by additional work in our laboratory as well (Anderson & Spear, 2009). This attenuation in sign-tracking among adolescent animals when compared to adults was surprising, and opposite to what we had hypothesized. It instead supports the suggestion that incentive salience for a discrete cue predicting food reward may be lower during adolescence than at maturity. To the extent sign tracking represents a valid index of incentive motivation and generalizes to cues predicting other rewards, the findings could be interpreted to suggest that adolescents may not be more vulnerable to cue-induced craving for drug rewards. Although counter to our original hypothesis, these data are reminiscent of findings from human fMRI work showing adolescents to exhibit less recruitment of the NAc than adults when anticipating a reward, while responding similarly to reward receipt, data interpreted to suggest that “adolescents selectively show reduced recruitment of motivational but not consummatory components of reward-directed
