Figure 4.

Anterior–posterior effect gradient. The figure shows an rLOESS curve fit (red) for mean t‐values at each integer MNI y‐coordinate. The distribution of mean t‐values after testing for longitudinal changes in MD suggests an increasing gradient from posterior to anterior segments. All WM‐skeleton t‐values were first extracted from the raw statistical t‐map output testing for MD increases over time across all participants. T‐values at each y‐coordinate were averaged and analyzed using rLOESS curve fitting in Matlab. A sagittal section of the MNI‐template T1‐brain is used as background and aligned so that the anatomy corresponds to the respective MNI y‐coordinates on the x‐axis of the diagram. Note that neither the y‐axis nor the x‐axis of the diagram starts at the conventional 0 levels.