Fig. 5.

Fibre tractography regions-of-interest used to identify fixels with a test-statistic signal. All tracts were extracted from a whole-brain tractogram (Fig. 4c) using the SRI24 atlas (Fig. 4d) and edited by a neurologist. All tracts in rows 1–4 are coloured by streamline direction (red: left–right, blue: inferior–superior, green: anterior–posterior). The bottom row illustrates tracts that would be affected in an Alzheimer's-like pathology, chosen to simulate diseases that have a more global pathology. Alzheimer's-like fibre tracts include the left arcuate fasciculus (yellow), cingulum (dark blue), anterior commissure (pink), uncinate fasciculus (green), anterior corpus callosum (red), and posterior corpus callosum connecting the left and right precuneus (light blue).