Fig 1. Distribution of significant voxels with increased gray matter density in the mathematicians relative to the control subjects (statistical significance is thresholded at P < .0001, uncorrected). Only clusters of voxels consisting of at least 100 voxels are displayed. The 3D overlay images demonstrate the regions with significantly increased gray matter density (red-labeled regions) in the mathematicians compared with the control subjects. The anatomic sectional images show the overlay of the results on the normalized T1-weighted images of a mathematician. The color scale on the T1-weighted images shows the ranges of T values.