“…It is difficult to speculate about mechanisms underlying the finding of heterogeneous development across the subcortical brain, including across hemispheres; however the patterns may relate to the different rates of maturation of the dopaminergic and serotonergic pathways (Casey & Jones, ; Chambers et al ., ; Lambe, Krimer & Goldman‐Rakic, ; Takeuchi, Matsushita, Sakai, Kawano, Yoshimoto & Sawada, ) and the differential distribution of these receptors in the subcortical brain (Brown, Crane & Goldman, ). For example, the amygdala, a structure that is both functionally associated with serotinergic activity (Hariri, Mattay, Tessitore, Kolachana, Fera, Goldman, Egan & Weinberger, ) and has nuclei that are more densely populated with serotinergic receptors relative to the other regions described in this study (Pazos, Probst & Palacios, ), did not show developmental change.…”