The neocortex constitutes the biggest part of the cerebral cortex of the brain. It is the evolutionary youngest part of the brain and can only be found in mammals. It is composed of six distict layers of neurons, the so-called cortical plate, which is established during embryonic development. First, glial cells originating from progenitor cells in the ventricular zone extend their processes throughout the cortex and anchor at the outer surface of the brain. This provides a scaffold of glial fibers. Second, neurons are produced from the same progenitor cells, migrate outwards along the glial fibers and estblish layer after layer of the developing cortical plate.