An MRI study of sex - and age - related differences in the dimensions of the corpus callosum and brain

Introduction Corpus callosum dimensions, morphology and sex-related differences have been of interest to scientists, because they influence the performance of callosotomies in patients with intractable epilepsy. Reports describing numerous conflicting studies have been published with respect to variations in the size of the corpus callosum relative to handedness, gender and age. Witelson [1] found that the corpus callosum was significantly larger in left-handed and ambidextrous persons. Kertesz et al [2] identified no differences in callosal size based upon handedness and gender. DeLacoste-Utamsing and Holloway [3] found the splenium to be larger in females. Hayakawa et al [4] found that callosal size decreases in both sexes, and that this reduction in size appears to transpire between the ages of 40 and 60. The corpus callosum is the main fiber tract connecting the two cerebral hemispheres. The role of the corpus callosum in brain function still is a matter of debate. There is a topographic organization of callosal fibers, which represents the cortical regions that are connected. Fibers connecting frontal regions travel through the anterior aspect of the corpus callosum, while fibers connecting occipital cortices travel through the posterior segment. In this study, we used magnetic resonance imaging (MRI) to measure the longitudinal dimensions of the corpus callosum and its various parts. We also measured the longitudinal and vertical dimensions of the brain, in order to define the relative topographic locations of the corpus callosum within the brain, and to search for any sexand age-related differences in dimensions or relative position.