Concept
Cerebral cortex
Overview
The cerebral cortex, also known as the cerebral mantle, is the outer layer of neural tissue of the cerebrum of the brain in humans and other mammals. It is the largest site of neural integration in the central nervous system, and plays a key role in attention, perception, awareness, thought, memory, language, and consciousness.
The six-layered neocortex makes up approximately 90% of the cortex, with the allocortex making up the remainder. The cortex is divided into left and right parts by the longitudinal fissure, which separates the two cerebral hemispheres that are joined beneath the cortex by the corpus callosum and other commissural fibers. In most mammals, the cerebral cortex is folded, providing a greater surface area in the confined volume of the cranium. Apart from minimising brain and cranial volume, cortical folding is crucial for the brain circuitry and its functional organisation. In mammals with small brains, there is no folding and the cortex is smooth.
A fold or ridge in the cortex is termed a gyrus (plural gyri) and a groove is termed a sulcus (plural sulci). These surface convolutions appear during fetal development and continue to mature after birth through the process of gyrification. In the human brain, the majority of the cerebral cortex is not visible from the outside, but buried in the sulci. The major sulci and gyri mark the divisions of the cerebrum into the lobes of the brain. The four major lobes are the frontal, parietal, occipital and temporal lobes. Other lobes are the limbic lobe, and the insular cortex often referred to as the insular lobe.
There are between 14 and 16 billion neurons in the human cerebral cortex. These are organised into horizontal cortical layers, and radially into cortical columns and minicolumns. Cortical areas have specific functions such as movement in the motor cortex, and sight in the visual cortex. The motor cortex is primarily located in the precentral gyrus, and the visual cortex is located in the occipital lobe.
Overview adapted from Wikipedia (CC BY-SA 4.0; see the article history for authors).
In the original texts
Passages from public-domain books where Cerebral cortex is discussed.
These subcortical systems are to some extent modifiable by racial and individual experience, but their reactions are chiefly of the determinate or stereotyped character, with a relatively limited range of possible reaction types for any given stimulus complex. "It is shown by the lower vertebrates, which lack the cerebral cortex, that these subcortical mechanisms are adequate for all of the ordinary simple processes…
John Dewey, Creative Intelligence
names the idea; opens on it
The cavity which one thus enters from without is named the fourth ventricle (4 in Figs. 32 and 33). One can run the probe forward through it, passing first under the cerebellum and then under a thin sheet of nervous tissue (the _valve of Vieussens_) just anterior thereto, as far as the _aqueduct of Silvius_. Passing through this, the probe emerges forward into what was once the cavity of the anterior vesicle. But…
William James, Psychology
states what it is
In all animals the brain is without blood, nor does it contain any veins, and it is naturally cold to the touch. The greater number of animals have a small cavity in the centre of the brain. And round this a membrane filled with veins: this membrane is like skin, and encloses the brain. Above the brain is the smoothest and weakest bone in the head--it is called sinciput.
Aristotle, Aristotle's History of Animals In Ten Books
states what it is
The cerebrum is not occupied with direct impressions from without but with the ideas of such impressions. Instead of the actual sensations produced in the body, and directly appreciated by the sensory ganglia, or primitive nervous centres, the cerebrum receives only the representations of these sensations; and its consciousness is called _representative_ consciousness, to distinguish it from the original or…
Herbert Spencer, Essays
states what it is
But the movements which are thus excited in the brain by the nerves variously affect the soul or mind, which is intimately conjoined with the brain, according to the diversity of the motions themselves. And the diverse affections of the mind or thoughts that immediately arise from these motions, are called perceptions of the senses (SENSUUM PERCEPTIONES), or, as we commonly speak, sensations (SENSUS). CXC. Of the…
René Descartes, Selections from the Principles of Philosophy
states what it is
Related ideas
- Epilepsy
- Motor cortex
- Language
- Mutation
- Neuron
- Sense
- Perception
- Memory
- Visual cortex
- Pathogen
- Thought
- Brain
- Broca's area
- Human brain
- Awareness
- Intelligence
- Hippocampus
- Human body
- Consciousness
- Attention
- Drug
- Corpus callosum
- Animal consciousness
Place in the tradition
Part of Consciousness.