There are two characteristic features of brain development during adolescence: a decrease in gray matter density and cortical thickness, likely reflecting synaptic pruning and myelination; and an increase in white matter (Sowell et al., 2004; Toga et al., 2006). These processes are not uniform across different brain regions (Sowell et al., 2002; Sullivan et al., 2011). Adolescent males exhibit steeper developmental slopes in gray matter reduction and white matter increase than females (De Bellis et al., 2001; Lenroot et al., 2007; Lenroot and Giedd, 2010; Raznahan et al., 2011). The observed decrease in theta ERO power in our study is consistent with the decrease in gray matter density and cortical thickness; perhaps the steeper trajectories of theta ERO power loss in males are related to their steeper trajectory of gray matter reduction. Trajectories of brain volumes of different regions and tissue types, as well as other features of cortical anatomy in pre-adolescents and adolescents, exhibit curvilinear properties which vary between regions (Lenroot and Giedd, 2008; Shaw et al., 2008; Giedd et al., 2010; Raznahan et al., 2011; Sullivan et al.,
