Cortical white matter: beyond the pale

Abstract

The tracts within the subcortical white matter and corpus callosum provide an anatomical connectivity that is essential for normal cognitive functioning. These structures are predominantly made up of axons that are myelinated or unmyelinated, and entering or exiting the overlying gray matter. As is increasingly recognized, however, the white matter territory is neither inert nor static. It has its own microenvironment, consisting of scattered neurons, abundant glia, and blood vessels; but at the same time it is an integrated component with the much more neuron dense gray matter.