“…One of the most enduring findings from diffusion tensor imaging (DTI) studies across the lifespan is the regionally selective distribution of low fractional anisotropy (FA) in frontal white matter with increasing age (Bennett and Madden, 2014;Bhagat and Beaulieu, 2004;Cox et al, 2016;Head et al, 2004;Madden et al, 2012;Pfefferbaum et al, 2005;Rojkova et al, 2016;Salat et al, 2005;Sexton et al, 2014;Vik et al, 2015;Zhang et al, 2010), a finding thathas been corroborated in non-human primates (Kubicki et al, 2018;Makris et al, 2007). An anteriorto-posterior gradient of fiber integrity, in which anterior fiber bundles are more susceptible to age-related degeneration than posterior fibers, has also been demonstrated in the corpus callosum using a variety of analytic approaches, including region-of-interest (ROI) analysis (Bender et al, 2016b;Madden et al, 2012;O'Sullivan et al, 2001;Pfefferbaum et al, 2005;Pfefferbaum and Sullivan, 2003;Salat et al, 2005;Sexton et al, 2014;Xie et al, 2016), voxel-based approaches (Hsu et al, 2008;Salat et al, 2005;Sexton et al, 2014;Zhang et al, 2010), and tract-based analyses (Bennett et al, 2010;Burzynska et al, 2010;Davis et al, 2009;Fjell et al, 2017;Lebel et al, 2012;Liu et al, 2018;Sala et al, 2012;Sullivan et al, 2001Sullivan et al, , 2010.…”