Fig. 1.

Self-administration of liquid sucrose in young adolescent, adolescents, and adult rats. a Number of rewards (i.e., lever presses during the active period) earned by the young adolescent (white circles), adolescent (gray circles), and adult (black circles) rats. b Number of active (circles) and inactive (triangles) lever presses during both the active and the time-out period. c Number of lever presses during the 20 s time-out period following delivery of the reward. d Sucrose consumption normalized to body weight. *p < 0.05, adults different from the two adolescent groups; #p < 0.05, adults different from the young adolescent groups