Sexual dimorphism and handedness in the human corpus callosum based on magnetic resonance imaging

Abstract

The corpus callosum (CC) is a major anatomical and functional commissure linking the two cerebral hemispheres. With MR imaging in the sagittal plane, the corpus callosum can be depicted in great detail. Mid-sagittal magnetic resonance images of 80 normal individuals were analyzed to assess whether or not the morphology of the corpus callosum and its parts are related to sex and handedness. The subjects were 40 males (20 right-handers and 20 left-handers) and 40 females (20 right-handers and 20 left-handers). The midsagittal area of the corpus callosum was divided into seven sub-areas using Witelson's method. The most striking morphological changes concerned left-handers, who had larger areas of the anterior body, posterior body and isthmus than right-handers. In addition, right-handed males had larger rostrums and isthmuses than right-handed females. These significantly increased areas were related to handedness in right-handed males. However, left-handed males had larger anterior and posterior bodies than right-handed males. In contrast, there was no significant difference between left-handers and right-handers in females. The areas of the rostrum and posterior body of the corpus callosum increased significantly with sex in males. Moreover, there were no significant age-related changes in the total corpus callosum and sub-areas of the corpus callosum. In conclusion, these anatomical changes in corpus callosum morphology require taking the sexual definition and dominant handedness into consideration.

Selective increase in posterior corpus callosum thickness between the age of 4 and 11 years

“…Handedness is a frequently discussed factor when addressing structural differences in the corpus callosum. Non-right handed adult participants are frequently reported to exhibit larger mid-sagittal corpus callosum area than right-handed individuals (e.g., Habib et al, 1991;Tuncer et al, 2005;Witelson, 1989), although not consistently (e.g., Jancke et al, 1997;Luders et al, 2010a;Westerhausen et al, 2004). However, the present findings are in line with Luders et al (Luders et al, 2010b), who also did not find any handedness-related corpus callosum differences in a developing sample.…”

Preliminary sex differences in human cortical BOLD fMRI activity during the preparation of increasingly complex visually guided movements

“…Sex differences in the structure of the human corpus callosum have been noted in the scientific literature for many years. Although this literature is considered by many to be controversial, sex differences in the structure of the corpus callosum continue to be reported (for recent examples see Dubb et al, 2003;Suganthy et al, 2003;Westerhausen et al, 2004;Shin et al, 2005;Tuncer et al, 2005). The corpus callosum is the main route of interhemispheric cerebral connectivity in the brain, and therefore could be involved in the sex differences in the symmetry of activity observed both here and in other studies.…”

Corpus Callosum Anatomy in Right-Handed Homosexual and Heterosexual Men

“…This was particularly true for the isthmus (the posterior region of the body of the CC), which showed a 60% difference between hand-preference groups (Witelson, 1989) and a significant correlation with degree of hand preference (r = -.67) (Witelson & Nowakowski, 1991). This association between handedness and CC anatomy has been replicated in numerous subsequent MRI studies (e.g., Cowell, Kertesz, & Denenberg, 1993) and especially between handedness and callosal isthmus (e.g., Tuncer, Hatipoglu, & Ozates, 2005), although some studies which did not use the consistent-nonconsistent handedness dichotomy found no evidence for a structure-function association (Luders et al, 2003;Steinmetz et al, 1992). An MRI study using diffusion tensor imaging (DTI) found greater molecular diffusion, indexed by fractional anisotropy, in left handers, interpreted to indicate a different microstructure, such as a greater number or density of axons in the CC of left-than righthanded men (Westerhausen et al, 2003).…”