neocortex

The neocortex is the part of the cerebral cortex that is characteristic of mammals. It comprises the majority of the cortex, enveloping the older archicortex and paleocortex, and accounts for roughly 90 percent of the human cerebral cortex. The neocortex is a six-layered sheet of neural tissue, with layers labeled I to VI. It contains a mix of pyramidal excitatory neurons and various inhibitory interneurons and forms extensive horizontal and vertical connections that support complex information processing. The neocortex is organized into functional areas, commonly mapped in Brodmann areas, including primary sensory and motor cortices and multiple higher-order association areas. Information from the thalamus and other brain regions is relayed to the neocortex, which in turn projects to cortical and subcortical targets, forming distributed networks that underlie perception, movement planning, language, attention, and higher cognition. Cortical columns or minicolumns are proposed as basic processing units that span the six layers.

Developmentally, neocortex forms through an inside-out pattern in which neurons destined for deeper layers migrate first, followed by neurons forming the superficial layers. Evolutionarily, the six-layered neocortex is a hallmark of mammals and is expanded in primates, associated with advanced cognitive capabilities.

Clinical note: injury or disease affecting the neocortex can produce deficits in sensation, motor control, language, memory, or executive function depending on the region damaged.