Figure 1.

Schematic overview of ROI placement and tract reconstruction. For the CB, four ROI sets were strategically placed on color-by-orientation maps to reconstruct the dorsal and ventral portions of the CB in each hemisphere. The anterior dorsal ROI (#1) is outlined on three consecutive coronal slices in which the anterior commissure is most notable. The posterior dorsal ROI (#2) and posterior ventral ROI (#3) are outlined in the same view on two consecutive coronal slices at the posterior disjunction of the corpus callosum in the first two slices in which the corpus callosum appears disjointed. Finally, the first coronal slice showing the middle cerebellar peduncle was selected for outlining the anterior ventral ROI (#4). Tractography was filtered through a midline exclusion region to exclude any interhemispheric fibers (mostly corpus callosum). For the UF, two ROI sets were drawn on FA maps on a single coronal slice adjacent to the most anterior point of the fornix and placed in the stem of the anterior temporal lobe and around the white matter of the anterior floor of the external/extreme capsule. By retaining only those tracts with paths that connected both regions of interest (the “and” approach), we ensured that fibers were selected that exclusively belonged to the UF. For the SLF, the most dorsal part was identified in the axial view on color-by-orientation maps, usually one or two slices above the body of the corpus callosum. The SLF was then outlined from the superior-to-inferior direction in approximately five consecutive axial slices.