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60 CHARACTERISTICS OF BRAIN AND BEHAVIORFigure 3-1 Top, child to adolescent statistical map for the negative age effects representinggray matter density reductions observed between childhood and adolescence; bottom,adolescence and adulthood. These maps are three-dimensional renderings of the traditionalstatistical maps shown inside the transparent cortical surface rendering of one representativesubject’s brain. Lobes and the subcortical region were defined anatomically on thesame subject’s brain. Color coding is applied to each cluster based on its location withinthe representative brain. Clusters are shown in the frontal lobes (purple), parietal lobes(red), occipital lobes (yellow), temporal lobes (blue), and subcortical region (green). Seecolor insert. (Sowell et al., 1999b; Sowell et al., 1999a.)between individuals and during development. When brain volume data sets arespatially registered without taking this variability into account, cortical anatomicalregions are not well matched across subjects, particularly where sulcal patternvariability is highest. CPM methods, on the other hand, can be used to assess groupdifferences in cortical anatomy while accounting for the differences in sulcal locationacross subjects and also can be used to measure cortical asymmetries (Sowellet al., 2002b; Thompson, Moussai, et al., 1998). Briefly, a 3-D geometric modelof the cortical surface is extracted from the MRI scan of each subject (MacDonald