Fig. 2.

Widespread significant associations of the 3 orthogonal eigenvalues of the diffusion tensor with age across the WM skeleton. The effect size of positive age associations of the primary eigenvalue is smaller than those of the secondary and tertiary eigenvalue in lateral WM regions, and larger than those of the secondary and tertiary eigenvalue in medial WM regions. In these medial WM regions, the effect size of the positive age associations of the secondary eigenvalue is smaller than of the tertiary eigenvalue, and the secondary eigenvalue also displays insignificant or negative age associations in certain parts of the medial WM. Note that the contrast is the effect size of metric per year derived from a linear regression and displayed only in voxels with significant correlations with age. Voxels of the WM skeleton without significant correlations with age are displayed in white. Abbreviations: WM, white matter.