Representative diffusion time dependence of DTI metrics: MD (mean diffusivity), PD (parallel diffusivity), RD (radial diffusivity), and FA (fractional anisotropy) in three white matter regions and three gray matter regions of a healthy subject. GCC: genu, BCC: body, and SCC: splenium of the corpus callosum. TL: temporal lobes. PF: posterior fossa, and ICG: insula/cingulate gyri. The figure is reprinted with permission from (Tan et al., 2020).