in DTI characteristics of cortical and subcortical GM regions, pointing to various structural and physiological mechanisms to explain the findings (Camara et al., 2007, Chanraud et al., 2009, Douaud et al., 2009, Hasan et al., 2009, Lebel et al., 2008, Pfefferbaum et al., 2010a, Wang et al., 2010a, Zhan et al., 2012, Zhao et al., 2012). The utility of DTI analysis in both WM and GM is becoming increasingly evident with animal models, shedding light on the microarchitecture of the WM, where lower axial diffusivity (AD) is interpreted as a specific marker of axonal damage, loss, and density (Harsan et al., 2006, Sun et al., 2006) and higher radial diffusivity (RD) as a marker of dysmyelination and demyelination (Concha et al., 2010, Harsan et al., 2006, Mills and Tamnes, 2014, Tyszka et al., 2006), and as evidence of various physiological processes and changes in the GM. Therefore, analysis of multiple DTI measures, such as AD and RD together with FA, may aid in interpreting WM and GM findings. For example, examining the relative contribution of higher RD that suggests demyelination and lower AD that suggests lower axonal density would more specifically explain lower WM integrity (Alexander et al., 2007) and
