Aim: 

Present study aimed at describing the topography of corpus callosum (CC) fibres in patients with brain lesions, using fMRI and DTT.

Methods: 

Data from 4 patients were collected with a 1.5 T magnet. L.M. and D.B. had partial anterior callosal resection, M.C. partial posterior, S.M. a tumoral lesion in the right parietal cortex. L.M. and M.C. received tactile and gustatory stimuli, S.M. tactile and D.B. visual stimuli.

Results: 

Taste stimuli evoked bilateral activation of primary taste area (GI) in both M.C. and L.M. and in M.C. also an activation in the anterior spared CC. Tactile stimuli to the hand evoked activation of bilateral first somatosensory area (SI) in L.M., of contralateral SI only in M.C., and in L.M. also an activation focus in the spared posterior body of CC. Tactile stimuli to either foot activated contralateral SI in S.M. The tumor displaced the SI foot zone in the right hemisphere. In this patient one focus, evoked by right foot stimulation, was observed in the posterior CC, consistently with control subjects; a second one, activated by left foot, more anterior. Visual stimuli evoked in D.B. bilateral activation in primary visual area (VI) and a focus in the spared splenium of the CC. DTT analysis revealed in L.M. that fibres connecting areas SI of the two hemispheres crossed the posterior body of CC and those linking areas VI crossed the splenium, as in controls. In M.C., fibres from GI reach the contralateral side through the anterior CC, as in control subjects. In D.B. fibres connecting areas VI of the two hemispheres crossed the splenium; GI and SI are disconnected from the opposite hemisphere. In S.M., fibres from foot representation of left SI crossed the CC posteriorly, as in control subjects; fibres from foot region of right SI run more anteriorly.

Conclusion: 

Present results confirm previous findings on the functional topography of the CC obtained with fMRI and DTT in intact subjects.

Supported by MIUR (Cofin 2005).