In general, prospective longitudinal studies (reviewed in Paus, 2010) have verified cross-sectional observations and have provided the essential data to model developmental trajectories of regional brain growth. In particular, developmental patterns derived from longitudinally-acquired T1-weighted MRI data indicate heterochronicity and trajectory differences by brain region and sex (Giedd et al., 1999; Lenroot et al., 2007; Sowell et al., 1999; Sowell et al., 2004b). The brain size of boys is typically upwards of 10% larger than that of girls (Dekaban and Sadowsky, 1978; Goldstein et al., 2001). Brain growth in girls starts and ends earlier than that in boys, peaking at 10.5 years in girls and 14.5 years in boys and declining thereafter (Lenroot et al., 2007). Regionally, the neocortex follows a curvilinear trajectory (Gogtay et al., 2004; Lenroot et al., 2007; Shaw et al., 2008), whereas allocortex and medial temporal structures follow a linear path (Gogtay et al., 2004). Growth in cortical regions is earlier for both sexes in posterior cortical than anterior regions, being about 7 to 10 years in occipital and parietal cortices and 10 to 13 years in frontal regions (Shaw et al., 2008).
