Figure 1.

Combined fMRI/DTI procedure to track CMFs. a, Tracked fibers after first tracking step: a large ROI (blue rectangle) was set that covered the fMRI-defined M1 face, hand, and foot representations of both hemispheres. b, A second ROI (blue rectangle) was placed within the area of the CC identified by the first tracking step, and fiber tracking was performed again. c, A target ROI (blue rectangle) was centered on the knob of the right precentral gyrus, an accepted anatomical landmark for the M1 hand representation (Yousry et al., 1997). The closely adjacent fMRI-defined M1 hand area is depicted in green. d, Only those tracked fibers projecting into this target ROI were retained. Note that, because of the tracking procedure that was started bidirectionally from the seeds in the CC, fibers are retained also in a homologous region of the hand area of the left M1. A similar procedure was performed for the fMRI-defined M1 lip (magenta in a, b) and foot areas (orange; tracked fibers not shown). e, Selected voxels for FA calculation (purple) superimposed on the tracked hand CMFs (green), axial view at high magnification. f, Data from the same subject as in e, midsagittal view. R, Right.