Segregation of the Brain into Gray and White Matter: A Design Minimizing Conduction Delays

Abstract

A ubiquitous feature of the vertebrate anatomy is the segregation of the brain into white and gray matter. Assuming that evolution maximized brain functionalist-4, what is the reason for such segregation? To answer this question, we posit that brain functionary requires high interconnectivity arsd short conduction delays. Based osi this assumption we searched for the optimal brairs architecture by comparing different candidate designs. We found that the optimal design depends on the number of neurons, interrseworsai connectivity, and axon diameter, in particular, the requirement to connect neurons with many fast axons drives the segregation of the brain into white and gray matter. These results provide a possibie explanation for the structure of various regions of the vertebrate brain, suich as the mammalian neocortex and rseostriatum, the aviars telencephalon, and the spinai cord. Copyright: © 2005 Wen and Chkiovskii.