Fig 1. Orthogonal axial/coronal (A) and axial (B) projection of T1-weighted MR images with fiber tracts depicted in color in the healthy volunteer (violet and yellow, lip fibers; green and red, hand fibers; pale blue and dark blue, foot fibers) The hand and foot fibers of the corticospinal and the lip fibers of the corticobulbar tract can be clearly distinguished and visualized (A and B). The different fMRI activation areas used to choose the seed regions of interest are shown in color (A). The course of the fibers through the corona radiata follows the known somatotopic distribution (B). C, The results are shown from conventional DT tractography (in orange) as well as from fMRI-based fiber tracking with region-of-interest placement in the PMA of the lip of the right hemisphere (in green), projected on a coronal T1-weighted image of the healthy volunteer. fMRI activation (shown in yellow-orange) is visible in the PMA of the lip and supplementary motor area in both images. Clearly, the lip fibers are only visualized by using the fMRI-based fiber tracking approach and not with the conventional fiber tracking approach.