Research Article

Functional Topography of Human Corpus Callosum: An fMRI Mapping Study

Figure 4

Callosal BOLD effect evoked by tactile stimulation of different body regions in control subjects. (a), CC foci evoked by tactile stimuli to the hand in subjects Ca.C. ((a)1) and M.S. ((a)2). Activation was always in the central part of the CC. Tactile hand stimulation often activated also the splenium, shown in frame 2 (subject M.S.). (b), callosal foci evoked by tactile stimulation of proximal body regions (shoulder, thigh, and trunk) in subjects I.P. ((b)1), F.F. ((b)2), and E.G. ((b)3), respectively. (c), CC foci evoked by stimulation of distal body regions (arm, leg, and foot) in subjects E.G. ((c)1), I.P. ((c)2), and E.P. ((c)3), respectively. All foci lay in the posterior callosal region. Fibers arising from the activated anterior parietal cortex cross the CC through its central portion ((a)3, yellow arrow). On DTI image, a thin white line demarcates the CC. Numbers on each brain represent the Talairach coordinates ( , , ) of each focus (green arrows).