korteks

Korteks refers to the outer layer of an organ, most commonly the cerebral cortex of the brain. The term comes from Latin cortex, meaning bark, reflecting its position on the surface of the organ. In addition to the brain, other organs such as the kidney have cortical regions.

The cerebral cortex is the thin, convoluted layer that covers the cerebrum. It consists of gray matter on the surface and underneath lies white matter. In humans it is about 2–4 mm thick and is folded into gyri and sulci, enlarging the surface area. The cortex is traditionally described as the neocortex, which has six cellular layers, and other cortical areas with fewer layers known as allocortex. It is subdivided into lobes (frontal, parietal, temporal, occipital) and includes the insular cortex.

Functional organization includes primary sensory and motor areas (such as the primary motor cortex and primary sensory cortices) and numerous association areas that integrate information, support perception, language, memory, and executive functions. Visual, auditory, and somatosensory processing are organized along dorsal and ventral streams in some modalities. The cortex communicates with subcortical structures and other cortical regions to support behavior.

Development and evolution: The neocortex develops from neural progenitor cells and forms six layers; its expansion and gyrification are linked to cognitive capacities across mammals. Clinically, cortical damage can produce focal neurological deficits, and cortical atrophy is seen in many neurodegenerative diseases. Imaging studies focus on cortical thickness, folds, and activity.

Beyond the brain, korteks can refer to the outer region of other organs. For example, the renal cortex is the outer portion of the kidney, containing glomeruli and portions of the nephron and involved in filtration and reabsorption.