Do cortical areas emerge from a protocortex?

Abstract

The adult mammalian neocortex consists of numerous 'areas' distinguished from one another largely on the basis of distinctions in cytoarchitecture and connections. The developing neocortex, though, lacks many of these area-specific distinctions, and is more uniform across its extent. This less differentiated structure, here termed the 'protocortex' undergoes considerable modification after neurogenesis which results in the emergence of well-defined neocortical areas. To what extent, then, are neocortical areas predetermined? This issue is considered in the context of recent findings on the generation of the neocortex and its subsequent parcellation into distinct areas.