Findings on white matter microstructure provide further evidence of different neuromaturational trajectories for boys and girls. In a whole-brain voxelwise DTI study of 106 children and adolescents 5–18 years of age, males had higher FA in bilateral frontal white matter areas, right arcuate fasciculus, and left parietal and occipito-parietal regions, while females showed higher FA in the splenium of the corpus callosum (Schmithorst et al. 2008). Females displayed age-related increases in FA in all regions, whereas males did not. Other findings suggest higher FA in the genu in adolescent males compared to females (Silveri et al. 2006), while fiber tract analysis of 31 children and adolescents documents no sex-related FA differences (Eluvathingal et al. 2007). It is possible that power differences in voxelwise versus tractography methods and in sample size contribute to discrepant findings.
