Neocortex

From Citizendium, the Citizens' Compendium
Jump to: navigation, search
This article is a stub and thus not approved.
Main Article
Talk
Related Articles  [?]
Bibliography  [?]
External Links  [?]
Citable Version  [?]
 
This editable Main Article is under development and not meant to be cited; by editing it you can help to improve it towards a future approved, citable version. These unapproved articles are subject to a disclaimer.

The neocortex (literally translated "new coat or layer") is the six-layered outer layer of the mammalian brain. It consists of vertically organised cortical columns as discovered and described by Vernon Mountcastle. In higher mammals and primates such as humans the neocortex has adapted a highly folded structure, with bumps (gyri) and valleys (sulci) making up the typical surface appearance of the cortex. This structure of columns is preserved all across the surface of the cortex and it is now believed that only the connectivity patterns and cell density distinguish the function of one area of cortex from another. This is why the cortical macrocolumn, which consists of about 60.000 neurons and about a thousand minicolumns in the human cortex, is considered to be the basic 'computing' unit of the neocortex. There are about 20 billion neurons in the human neocortex (throughout postnatal life), and about 30 billion glia cells (these numbers, and also the percentages of different kinds of glia cells, vary strongly with gender and also a bit with age).

The neocortex is considered to be the seat of intelligence, all higher brain functions such as thought, perception, consciousness, memory, problem solving, creativity etc. are all considered to be functions of the common algorithm on which the neocortex operates. it consists of a large number of tightly packed neurons with their dendrites and axons and sitting atop a large amount of long distance axons covered with myelin that connect the different areas of the neocortex and connects it to the various older parts of the brain. The first type of tissue is called the grey matter and the 'box of cables' below it is called the white matter. It is believed that the neocortex is organised in a hierarchial structure ie. sensory input comes in and goes through a hierarchy of cortical areas and the higher up the hierarchy you go, the more abstract the representations of the cortex become.

Organisation of the cortex

The cortex consists of six layers, differentiated by the cell types and connectivity patterns that occur within them.


Evolution Of The Neocortex

Functions Of The Neocortex