Figure 1.

Images from the youngest and oldest adults required the most volume displacement during normalization, but visual inspection demonstrates that there were no DARTEL normalization errors due to this displacement. (A) Jacobian determinant images, that reflect the degree of volumetric displacement during normalization, were obtained from the DARTEL gray matter flow fields. There was significant age-related variation in the extent to which regions surrounding the ventricles and CSF in general required displacement during normalization (1% FDR). The results are overlaid on the study-specific DARTEL template. (B) An estimate [eigenvariate from the age-related effect shown in (A)] of how much each subject's lateral ventricles had to be displaced to fit to the template is plotted across age demonstrating that many younger, middle-aged, and older subjects required little ventricle displacement. Note that total gray matter volume was not related to the amount of ventricular displacement (GM, gray matter). (C) Visual inspection of the normalized gray matter images in three young female subjects and three of the oldest female subjects [labeled numerically in (B)] requiring the most volume displacement demonstrates that all were appropriately normalized to a common space. Note the close correspondence in the position of the head of the caudate across the six subjects (red arrows). Note also that there were areas where white matter regions were segmented as gray matter in the older adults (yellow arrows) and identified using SBM (Figure 2).