Fig. 4.

Comparison of white matter degeneration between primary progressive aphasia (PPA) groups and Alzheimer's disease (AD) group. Top panel displays patterns of increased axial diffusivity (AX) (top), radial diffusivity (RD) (middle), and trace diffusivity (TR) (bottom) in semantic variant PPA (sv-PPA) compared with AD. Bottom panel displays patterns of increased AX in AD compared with nonfluent/agrammatic variant PPA (nv-PPA). Results are overlaid on representative sections derived from the average fractional anisotropy skeleton. The right hemisphere is shown on the left. Color bars (bottom) code level of significance (family-wise error corrected p value).