The basal ganglia are a collection of subcortical nuclei (caudate, putamen, globus pallidus, subthalamic nucleus, and substantia nigra) that are involved in circuits mediating movement, higher cognitive functions, attention, and affective states. Basal ganglia anomalies have been reported for almost all neuropsychiatric disorders that have been investigated by neuroimaging (Giedd et al. 2006). Because of the small size and ambiguity of MR signal contrast of the borders defining the structures, only the caudate, putamen, and globus pallidus are readily quantifiable by MRI, and reliable automated techniques have only been established for the caudate. Like cortical GM the caudate follows an inverted U shape developmental trajectory, peaking at age 10.5 years in girls and 14.0 years in boys (see Fig. 2f). The shape of the caudate developmental trajectory is more similar to that of frontal and parietal gray matter than temporal supporting the notion that brain regions that share extensive connections also share similar developmental courses.
