Fig. 1: Estimation of GWC.

A illustrates the estimation of gray/white matter contrast (GWC). The pial surface is marked in red while the gray-white matter border is marked in white. Blue lines indicate points where gray and white matter signal intensities were extracted. Gray matter signal intensity was measured from six points from 10–60% into gray matter from the gray-white matter border to avoid partial volume effects and contamination from CSF. White matter signal intensity was extracted from 10 points from 0.15 mm to 1.5 mm into the subjacent white matter to avoid bias from cortical thickness. B shows the mean GWC across the cortex, where regions with more similar signal intensities in gray and white matter have lower GWC and are highlighted in red.