Stages of Cerebral Neocortex Development

The basic stages of cerebral neocortex development can be plainly stated. Cells produce, migrate and grow. The way this occurs however, is more detailed. The cerebral hemispheres are the left and right regions of the brain. The cortex (or neocortex) is the outer layer, commonly referred to as gray matter. It plays a prominent role in everything from attention and memory to language and perceptual awareness. Man's superior intelligence over beast is believed to be related to this unique neocortex.

Neocortex Layers

• The surface of a human neocortex is unique to man. According to the Brain Engineering Laboratory at Dartmouth College, the neocortex makes up the vast majority of the human brain. The various stages of development result in a structured six-layer neocortex. The horizontal group of layers is commonly designated by Roman numerals from one to six. The first is on the outer surface, and the the last (sixth) is the inner core. All mammals have a neocortex, but not with the same type of surface. No mammal has a neocortex with the same complex six-layered structure as a human's.

Pyramidal Neurons Migrate

• Pyramidal neurons are cells that are produced and found in the preplate of the brain. These neurons migrate from the preplate area, specifically from the ventricular and subventricular zones. Pyramidal neurons move on to mature and eventually reside in the cortical plate, where they continue to diversify. Horizontal cell axons migrate into the unoccupied prelate area, along with dendrites from pyramidal cells. These new arrivals are responsible for splitting the preplate and creating the marginal zone.

First Layers to Develop

• In the developmental process of a mature neocortex, the marginal zone becomes the first layer. It is actually a superficial layer, with an underlying layer called the subplate.

  The cortical plate is what makes up the deepest layers of the neocortex. The cortical plate area is designated as layers five and six. These layers, however, actually develop long before layers two through four.

Last Layers to Develop

• The word neocortex stems from the prefix "neo," which means "new." This term applies because the neurons that are the last to be born are new and less mature. The new arrivals are identified as layers two, three and four, and they make up the upper layers of the neocortex. A healthy neocortex is crucial to a human's thought process and socialization habits. According to The National Library of Medicine, "The neocortex is the brain structure that handles the more demanding cognitive and social skills."

The Neocortex Surface

• The Oxford Journals include information about the brain functions of humans and higher mammals. It credits higher cognitive abilities to the extensive expansion of neocortical surface area and complexity in higher mammals, especially primates. While rodents and small mammals have a smooth neocortex, primates and larger mammals have wrinkles and deep grooves. The various folds create an expanded surface area. This gives the neurons more room to work, so they are able to process and integrate huge volumes of information better.