The folded surface of the cerebral cortex contain a mosaic of functionally distinct areas which connect via a network of nerve fibres in the sub-cortical white matter. This network determines, in part, the computations that the cortex performs. These data's complexity make it possible to find subsets of connections to support virtually any theory of cortical organization. Therefore, I analysed collated anatomical data quantitatively to see if the 3D folding of the cortex is in fact related to wiring. Thus the development of the cortex does coordinate folding with connectivity in a way that produces smaller and faster brains.
Local connections are denser within gyri than across sulci.
The ratio of the number of observed to expected connections is plotted against connection weight. Thus natural selection has produced a 3D arrangement of areas that is not optimal for minimizing wire. Cortical connections, observed and expected. The cortex shows efficient folding and local wiring. Probabilities were calculated using Chi Squared.