Morphometry of the Sylvian fissure and the corpus callosum, with emphasis on sex differences.

The relationship between anatomical asymmetries in the perisylvian region and the sizes of different regions of the corpus callosum was investigated post-mortem in 40 brains of right-handed hospital admissions (20 males, 20 females) with no cortical involvement. There were no sex differences either in anatomical asymmetries or in regional size of the callosum. There was a negative correlation between the absolute value of Sylvian fissure (planum temporale) asymmetries and the size of the isthmus in males but not in females. Further, there was a significant negative correlation between the size of the Sylvian fissure (or planum temporale) and the size of the callosal mid-body in males but not in females. There was no correlation between the asymmetry of the planum temporale magnitude of left-right and total size of the planum (left+right). These findings constrain theories about the ontogenesis of hemispheric specialization through changes in callosal connectivity and about sex differences in interhemispheric organization.