In contrast, the marked developmental peaks in DA receptor density seen in dorsal striatum during adolescence is followed by substantial pruning of these receptors during the adolescent transition, characterized by a loss of 1/3 – 1/2 of the DA receptor population between early adolescence and young adulthood, a loss evident in both human autopsy material and in studies using animal models (e.g., Seeman et al., 1987; Tarazi & Baldessarini, 2000; Teicher et al., 2003). The NAc likewise shows peak D1- and D2-R levels during adolescence, although the subsequent pruning there seems relatively modest, with reports of significant declines of 20–35% or so between early adolescence and young adulthood (e.g., Andersen, 2002; Tarazi & Baldessarini, 2000;) contrasting with a lack of significant pruning in other studies (e.g., see Andersen et al., 2000).
