Why are the folds in the human brain important? What’s different about surface area vs sheer volume?
In: Biology
The neocortex (the wrinkly, outside part of the brain) is comprised of very many “cortical columns”. If you picture the neocortex flattened out like a napkin, the height of a column is the thickness of the napkin. So it seems that evolution wanted columns of a particular height, and the wrinkling was to increase the surface area of the napkin. In other words, humans evolved more columns rather than taller columns. From this you can infer that there’s something fundamental about a column as a processing unit, and columns like to exist in 2D arrays.
It seems that for some reason, the brain puts all its grey matter on the surface. Grey matter is the body of neurones, including the bits that connect them to other neurones. The white matter inside the brain is just a bunch of long axons, that are a bit like the railways between cities – there’s not a lot going on, just transporting stuff between two places where lots of stuff is going on. Because grey matter is only found at the surface, wrinkling the brain increases the amount of grey matter that can be had.
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