Anatomical Asymmetries in Language-Related Cortex and Their Relation to Callosal Function

Lateralization of linguistic and visuospatial functions has anatomical correlates that can be observed in gross brain anatomy, especially in the size and position of the planum temporale. Furthermore, the Sylvian fissure has qualitatively distinct morphologies that are unequally distributed across the hemispheres. These correlates may reflect the differential development of specific architectonic areas in the two hemispheres, which are of direct relevance for lateralized function. Additionally, interhemispheric connectivity is inversely related to anatomical asymmetry in males more than in females, indicating that there may be sex differences in the interhemispheric organization for language. We discuss these findings in the context of the development of hemispheric asymmetry and its relation to interhemispheric interaction, both from an ontogenetic and a phylogenetic viewpoint.