Brain Gyrification and its Significance

Comparsion of Human, Macaque, and Mouse Brains and Extent of Gyrification. Credit to J. Horton.

Gyrification in the brain, also known as convolution, is process of cortical folding that leads to the wrinkle like appearance of mammal brains. It is the basis for the presence of gyri and sulci (hills and valleys) in cerebral cortex. The extent of gyrification of brains is highly implicated as being positively related to species intelligence. The basic idea is that gyrification allows for (or is a result of) greater surface area of cortical neurons within the same skull volume. However the exact mechanism by which this occurs, its true significance, and the implications of differences within species is not conclusively known or explored. With this in mind, this wiki seeks to explore the literature on the chemical or physical cause/mechanism of gyrification, differences in anatomy across species and within species, and possible theories of significance that could be derived based on previous findings.

Classification and Medical Conditions

Lissencephaly vs. Normal Brain. Source: http://www.hxbenefit.com/lissencephaly.html

Left to Right: normal, polymicrogyria, lissencephaly. Credit: Lefèvre and Mangin, 2010l

Relation to Species Intelligence

Brain Size to Body Weight Ratios Across Species

Figure 1: Relationship between brain size and body size in selected mammals. Credit: Roth & Dicke, 2005

Figure 2: EQ Values Across Species. Credit: Macphail

Gyrification Across Species

""Figure 3:"" Gyrification Across Species. Credit to Patricia Anne Kinser (2000). Source: http://serendip.brynmawr.edu/exchange/brains