Functional topography of human corpus callosum: an FMRI mapping study.

Mara Fabri,Gabriele Polonara

doi:10.1155/2013/251308

Mara Fabri, Gabriele Polonara

Open Access

https://doi.org/10.1155/2013/251308

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Abstract

The concept of a topographical map of the corpus callosum (CC) has emerged from human lesion studies and from electrophysiological and anatomical tracing investigations in other mammals. Over the last few years a rising number of researchers have been reporting functional magnetic resonance imaging (fMRI) activation in white matter, particularly the CC. In this study the scope for describing CC topography with fMRI was explored by evoking activation through simple sensory stimulation and motor tasks. We reviewed our published and unpublished fMRI and diffusion tensor imaging data on the cortical representation of tactile, gustatory, auditory, and visual sensitivity and of motor activation, obtained in 36 normal volunteers and in 6 patients with partial callosotomy. Activation foci were consistently detected in discrete CC regions: anterior (taste stimuli), central (motor tasks), central and posterior (tactile stimuli), and splenium (auditory and visual stimuli). Reconstruction of callosal fibers connecting activated primary gustatory, motor, somatosensory, auditory, and visual cortices by diffusion tensor tracking showed bundles crossing, respectively, through the genu, anterior and posterior body, and splenium, at sites harboring fMRI foci. These data confirm that the CC commissure has a topographical organization and demonstrate that its functional topography can be explored with fMRI.

Highlights

The corpus callosum (CC) connects the cerebral hemispheres and provides for interhemispheric integration and transfer of information
Subsequent electrophysiological [5] and neuroanatomical findings [6, 7] obtained from nonhuman primates after selective cortical ablation or tracing injections, plus a vast body of data ranging from postmortem investigations [8] to studies of patients with CC lesions or callosal resection, lent further support to the notion
In this paper we review our data showing the callosal activation evoked by a variety of peripheral sensory stimuli in a group of normal subjects and in 6 partial callosotomy patients

Summary

Introduction

The corpus callosum (CC) connects the cerebral hemispheres and provides for interhemispheric integration and transfer of information. Subsequent electrophysiological [5] and neuroanatomical findings [6, 7] obtained from nonhuman primates after selective cortical ablation or tracing injections, plus a vast body of data ranging from postmortem investigations [8] to studies of patients with CC lesions or callosal resection (split-brain subjects; [9]; see [10,11,12] for a review), lent further support to the notion Such organization seems to result in modalityspecific regions [13], where the anterior callosal fibers interconnecting the frontal lobes transfer motor information and posterior fibers, which connect the parietal, temporal, and occipital lobes bilaterally, are responsible for the integration of somatosensory (posterior midbody), auditory (isthmus), and visual (splenium) information.

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