Schematic of representative monkey brain levels selected for white matter analysis. Gray shaded areas represent the approximate extent of white matter collected for western blot analysis. Outlined areas represent regions of interest analyzed for MBP and PLP mRNA expression. A, Corpus callosum; B, Corona radiata; C, Internal capsule. Abbreviations: PFC, prefrontal cortical level; AS, Anterior (precommissural) striatal level; PS, Posterior (postcommissural) striatal level.