Gyrification is the process of forming the characteristic folds of the cerebral cortex.[1]
The peak of such a fold is called a gyrus (pl. gyri), and its trough is called a sulcus (pl. sulci). The neurons of the cerebral cortex reside in a thin layer of gray matter, only 2–4 mm thick, at the surface of the brain.[2] Much of the interior volume is occupied by white matter, which consists of long axonal projections to and from the cortical neurons residing near the surface. Gyrification allows a larger cortical surface area and hence greater cognitive functionality to fit inside a smaller cranium.
In most mammals, gyrification begins during fetal development. Primates, cetaceans, and ungulates have extensive cortical gyri, with a few species exceptions, while small rodents such as the rat, and mouse have none. Gyrification in some animals, for example the ferret, continues well into postnatal life.[3]
- ^ Rakic, P (October 2009). "Evolution of the neocortex: a perspective from developmental biology". Nature Reviews Neuroscience. 10 (10): 724–35. doi:10.1038/nrn2719. PMC 2913577. PMID 19763105.
- ^ Kandel, Eric R.; Schwartz, James H.; Jessell, Thomas M.; Siegelbaum, Steven A.; Hudspeth, A.J., eds. (2012) [1981]. Principles of Neural Science (5th ed.). New York: McGraw Hill. ISBN 978-0-07-139011-8.
- ^ Smart, IH; McSherry, GM (June 1986). "Gyrus formation in the cerebral cortex in the ferret. I. Description of the external changes". Journal of Anatomy. 146: 141–52. PMC 1166530. PMID 3693054.