Hemispheric differences in variability of fissural patterns in parasylvian and cingulate regions of human brains.

We have determined different patterns of fissurization in Broca's area, the gyrus of Heschl, the planum temporale, the inferior parietal lobe, and the cingulate sulcus. Such patterns were asymmetrically distributed, indicating increased folding on the left side in most cases. More folding can sometimes be related to a larger cortical area, resulting in increased processing capacities in the respective brain region. Furthermore, the brain regions associated with the asymmetrical sulci are involved in lateralized functions. Of special interest are the asymmetries observed in regions corresponding to the inferior parietal lobe (the accessory postcentral sulcus and the intraparietal sulcus), which, according to recent studies, is involved in linguistic working memory. We did not detect a tendency of distinct fissurization patterns in a given brain region to be associated with specific patterns in other fissures, indicating that the different fissure types develop independently in each brain region and can therefore be determined by local processes. These descriptions are of relevance to imaging studies that intend to establish correspondences between gross morphology and functional parameters such as behavior and brain activation.