neocortical

Neocortical is an adjective referring to the neocortex, the portion of the cerebral cortex that is most recently evolved in mammals and that constitutes the majority of the cortical mantle. The neocortex covers the older parts of the cortex (allocortex) and is distinguished by a six-layered laminar structure and diverse neuronal types.

The neocortex is organized into six cellular layers, I to VI, with distinct patterns of input and output. Layer IV is the primary recipient of feedforward sensory input from the thalamus in primary sensory areas; Layers II and III support intracortical communication and integration; Layers V and VI project to subcortical targets and provide feedback to the thalamus.

Functionally, the neocortex is involved in perception, motor control, and higher-order cognitive processes such as language, planning, and abstract reasoning. Different regions specialize for primary sensory and motor functions, as well as for association areas that integrate information across modalities. Neocortical circuits rely on excitatory pyramidal neurons and inhibitory interneurons arranged in columnar modules, and on extensive horizontal and feedback connections that support complex processing.

Developmentally, the neocortex arises from the dorsal pallium and forms during gestation with a characteristic inside-out pattern of neuronal migration that yields six mature layers. Evolutionarily, the neocortex expanded substantially in mammals, especially in primates, with enlargement of association and frontal areas.

Clinical relevance includes deficits arising from focal neocortical injury or developmental disorders affecting cortical connectivity, such as epilepsy, autism spectrum disorders, and aphasias, reflecting the central role of the neocortex in sensory, motor, and cognitive functions.