Aivokuorta

Aivokuorta, or the cerebral cortex, is the outer layer of the cerebrum in the brain. It is composed predominantly of gray matter and is folded into gyri and sulci, which increases its surface area and the number of neurons supported within the skull. Beneath the cortex lies white matter, made up of myelinated axons that connect cortical regions with each other and with subcortical structures.

In most mammals, including humans, the cortex is organized into six layered regions in the neocortex, each containing different neuron types such as pyramidal cells and interneurons. Some older parts of the cortex, called allocortex, have fewer than six layers. This layered organization supports a wide range of functions, from basic sensation to complex cognition, and varies in density and arrangement across different cortical areas.

Functionally, the cortex is commonly divided into lobes: frontal, parietal, temporal, and occipital, plus the insular region. Primary functional areas include the primary motor cortex in the frontal lobe, which controls voluntary movement; the primary somatosensory cortex in the parietal lobe, which processes touch and proprioception; the primary visual cortex in the occipital lobe; and the primary auditory cortex in the temporal lobe. Association cortices integrate information for higher-order processes such as language, memory, attention, and executive functions. Lateralization of functions is common, with certain abilities more dominant in one hemisphere.

Developmentally, the cortex forms and expands during gestation and continues to adapt postnatally. Evolutionarily, the cortex has expanded especially in mammals with greater cognitive demands, leading to more extensive association areas in humans than in many other species.

Damage to the cerebral cortex can cause region-specific deficits in perception, movement, language, or cognition, depending on the affected area.