Cerebral cortex facts for kids

Different parts of the cortex
have different functions

The cerebral cortex is a most important part of the brain. In humans, it is by far the largest part of the brain.

Though this cannot be seen directly, different parts of the cortex have different functions (see diagram). It plays a key role in memory, attention, perceptual awareness, thought, language, and consciousness.

It is a sheet of neural tissue that is outermost to the cerebrum of the mammalian brain. It has up to six layers of nerve cells. The human cerebral cortex is 2–4 mm (0.08–0.16 inches) thick.

In preserved brains, it is grey, so it is often called 'grey matter'. In contrast to gray matter that is formed from neurons and their unmyelinated fibers, the white matter below them is formed predominantly by myelinated axons interconnecting neurons in different regions of the cerebral cortex with each other and neurons in other parts of the central nervous system.

The surface of the cerebral cortex is folded in large mammals, such that more than two-thirds of it in the human brain is buried in the grooves.

Neocortex

The phylogenetically most recent part of the cerebral cortex, the neocortex, has six horizontal layers; the more ancient part of the cerebral cortex, the hippocampus, has at most three cellular layers. Neurons in various layers connect vertically to form small microcircuits, called 'columns'.

The neocortex is the newest part of the cerebral cortex to evolve. The six-layer neocortex is a distinguishing feature of mammals; it has been found in the brains of all mammals, but not in any other animals. In humans, 90% of the cerebral cortex is neocortex.

Allocortex

Other parts of the cerebral cortex are:

• Allocortex: fewer than six layers, more ancient phylogenetically than the mammals, evolved to handle olfaction and the memory of smells.
  • Archicortex (includes functions related to emotions and memory)
    • Olfactory cortex
    • Hippocampus
  • Paleocortex (3 three to five layers)

The cellular organization of the old cortex is different from the six-layer structure mentioned above.

Images for kids

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  Lateral view of cerebrum showing several cortices

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  Diagram of layers pattern. Cells grouped on left, axonal layers on right.

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  Micrograph showing the visual cortex (predominantly pink). Subcortical white matter (predominantly blue) is seen at the bottom of the image. HE-LFB stain.

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  Arterial supply showing the regions supplied by the posterior, middle, and anterior cerebral arteries.

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  Cortical blood supply

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  Neurogenesis is shown in red and lamination is shown in blue. Adapted from (Sur et al. 2001)

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  Depicted in blue, Emx2 is highly expressed at the caudomedial pole and dissipates outward. Pax6 expression is represented in purple and is highly expressed at the rostral lateral pole. (Adapted from Sanes, D., Reh, T., & Harris, W. (2012). Development of the Nervous System (3rd ed.). Burlington: Elsevier Science)

• 

  Some functional areas of cortex

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  Cortical areas involved in speech processing.

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  Hemodynamic changes observed on gyrencephalic brain cortex after an arterial vessel occlusion in IOS. The video has a speed of 50x to better appreciate the spreading depolarization over the brain cortex. Pictures are dynamically subtracted to a reference picture 40 s before. First we see the initial are of change at the exact moment where the middle cerebral artery group (left) is occluded. The area is highlighted with a white line. Later we appreciate the signal produced by Spreading Depolarizations. We see markedly the front of waves. https://doi.org/10.1007/s00701-019-04132-8

• 

  Lateral surface of the human cerebral cortex

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  Medial surface of the human cerebral cortex

See also

In Spanish: Corteza cerebral para niños