(Sowell et al., 1999, 2003; Gogtay et al., 2004). Particularly relevant to a review about the development of the dopamine system is evidence showing that the dopamine-rich frontal and striatal regions undergo significant maturational changes through adolescence (Giedd et al., 1996; Sowell et al., 1999), with a volumetric decrease in regions of the basal ganglia (Giedd et al., 1996, 1999). Similar to rodent findings, brain regions show sexual dimorphism across regions. Caudate volumes decrease during the adolescent years and are relatively larger in females (Giedd, 2004). In contrast to parietal, temporal and occipital lobes, large anatomical differences emerge between adolescents and adults in the frontal lobes and in the striatum (Sowell et al., 1999), suggesting that these two regions are relatively immature in adolescence compared to adulthood. Further, these findings suggest continued plasticity in these regions that may mediate dopamine-related behaviors and learning.
