[3] In the human brain, the cerebral cortex consists of the larger neocortex and the smaller allocortex, respectively taking up 90% and 10%.

It is found in the cingulate cortex (part of the limbic system), in Brodmann's areas 24, 25, 30 and 32, the insula and the parahippocampal gyrus.

Of all the mammals studied to date (including humans), a species of oceanic dolphin known as the long-finned pilot whale has been found to have the most neocortical neurons.

[13] The structure of the neocortex is relatively uniform (hence the alternative names "iso-" and "homotypic" cortex), consisting of six horizontal layers segregated principally by cell type and neuronal connections.

[14] However, there are many exceptions to this uniformity; for example, layer IV is small or missing in the primary motor cortex.

The neocortex is divided into regions demarcated by the cranial sutures in the skull above, into frontal, parietal, occipital, and temporal lobes, which perform different functions.

When the neurons are at rest and are hyperpolarizing, a period of inhibition occurs during a slow oscillation, called the down state.

When the neurons of the neocortex are in the excitatory depolarizing phase and are firing briefly at a high rate, a period of excitation occurs during a slow oscillation, called the up state.

This disruption of sensory information contributes to the progressive symptoms seen in neurodegenerative disorders such as changes in personality, decline in cognitive abilities, and dementia.

If damage is sustained to this area, patients do not develop anterograde amnesia and are able to recall episodic information.

[12] For a species to develop a larger neocortex, the brain must evolve in size so that it is large enough to support the region.

[19] The neocortex increased in size in response to pressures for greater cooperation and competition in early ancestors.