Figure 4.

Simplified illustration of the frontal aslant tract (FAT) and newly described transcollasal projections of the FAT. (a) FAT connecting the supplementary motor area (SMA) and inferior frontal gyrus (IFG). Right FAT shown in green and left FAT in blue. (b) Transcollasal FAT fibers originate from the previously described FAT. The fiber bundles transverse the corpus callosum (CC) connecting controlatereal premotor areas. (c) Proposed mechanism of permanent SMA syndrome. Dissection into the CC with complete separation of the SMA from the contralateral hemisphere may result in permanent SMA syndrome