Corpus callosum topography studied by means of functional resonance imaging and diffusion tensor tractography in patients with partial callosotomy to treat drug-resistant epilepsy

Combining functional magnetic resonance imaging (fMRI) with diffusion tensor tractography (DTT) affords novel opportunities to study cortical connections in the brain. The cortical lobes of the two hemispheres are interconnected by the corpus callosum (CC). We used fMRI and DTT to study three patients subjected to anterior or subtotal callosotomy for drug-resistant epilepsy. Taste, visual and tactile stimulation were applied to obtain data on callosal fibers. When the anterior portion of the CC was spared the taste stimulus reached the opposite hemisphere, whereas very few stimuli crossed the CC in patients with subtotal callosotomy. These data confirm in vivo the cortical topography of callosal fibers. The new techniques have opened exciting prospects for the functional study of cortical brain areas and their connecting pathways.