Mechanisms of cerebral cortical patterning in mice and humans

All the higher mental and cognitive functions unique to humans depend on th e neocortex ('new' cortex, referring to its relatively recent appearance in evolution), which is divided into discrete areas that subserve distinct fu nctions, such as language, movement and sensation. With a few notable excep tions, all neocortical areas have six layers of neurons and a remarkably si milar thickness and overall cell density, despite subtle differences in the ir cellular architecture. Furthermore, all neocortical areas are formed ove r roughly the same time period during development and provide little hint a t early developmental stages of the rich functional diversity that becomes apparent as development comes to an end. How these areas are formed has lon g fascinated developmental neuroscientists, because the formation of new co rtical areas, with the attendant appearance of new cortical functions, is w hat must have driven the evolution of mammalian behavior.