Cerebral cortical folding patterns in primates: Why they vary and what they signify

In each primate species, cerebral cortex has a distinctive pattern of folds. Cortical folds arise during development around the time that corticocortical projections between areas are established. Mechanical tension along these long-distance axons may be a major driving force that determines where folding occurs. The pattern of folds in three gyrencephalic primates (macaque monkey, chimpanzee, and human) as revealed by surface-based analyses provides support for this hypothesis. There are numerous commonalities in folding patterns that may reflect similarities in the layout of areas and their connections. Species differences in folding patterns may reflect differences in functional organization, including differential expansion of lateral parietotemporal and dorsolateral prefrontal regions in the human evolutionary lineage.