Cerebral cortex: its layers, areas and functions

April 22, 2024

As human beings, everything we feel, reason and perceive, as well as our ability to move and perform any activity, has its origin in our brain.

Throughout this article we will talk about the cerebral cortex as well as its layers and the different structures that compose it and the functions each of them has.

Related article: "Parts of the human brain (and functions)"

What is the cerebral cortex?

The cerebral cortex refers to the outer layer of the brain. This layer It is formed by thin film of nervous tissue that surrounds the surface of the cerebral hemispheres, being the primates that enjoy a cerebral cortex much more developed than the rest of animals.

Thanks to the correct functioning of the cerebral cortex, humans have the ability to perceive what happens to us and surrounds us, as well as to imagine, think, have capacity for judgment and decision and, finally, the ability to understand and produce language.

Although, as explained above, the cerebral cortex is a thin layer of neurons and neuronal connections, it is not homogeneous, since it is It is made up of six layers of cells , and each of them with specific and specific functions.

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Types of brain cortex

If we rely as much on the structural as phylogenetic perspective of the cerebral cortex, we can differentiate three different classes of this. These are the following.

1. Arquicorteza

Evolutely speaking, it is the oldest part of the cerebral cortex. Formed by the hippocampus, the architect is responsible for those automatic responses and physiological mechanisms responsible for survival .

2. Paleocortex

Philogenetically, the paleocortex is halfway between the most primary areas of the cerebral cortex and the most evolved . This class of cortex harbors the endings of the olfactory pathways, the olfactory brain of the people being found here.

3. Isocortex or neocortex

It is the area of the most recent crust, and the one in charge of processes of reasoning and abstract thinking .

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The layers of the cerebral cortex

As mentioned above, the cerebral cortex is made up of different layers of neuronal tissue known as gray matter. Each of these layers has a different functional specialization and has been originated at a different time in human evolution.

This means that, throughout our evolution and development as human beings, these layers have been increasing in quantity, which has implied a powerful development of our cognitive and intellectual capacities in comparison with other animal species.

These layers are the following.

1. Molecular layer

The molecular layer is the outermost, and therefore most recent in origin, of all strata of the cerebral cortex.

Also known as a plexiform layer , is essentially a synaptic layer formed by a thick network of neuronal fibers.

2. External granular layer

The second layer that makes up the cerebral cortex is the outer granular layer. This is formed by a large number of small stellate and pyramidal cells .

The axons of this layer infiltrate the molecular layer entering more submerged areas of the cerebral cortex, coupling with different areas of the cortex.

3. External pyramidal layer

The external pyramidal layer It gets its name from the type of cells that make it up: the pyramidal cells . These cells direct their axons to other areas of the cortex and to other subcortical destinations in the form of projection, association and commissural fibers.

4. Internal granular layer

This layer consists essentially of a compact mass of stellate cells, most of which receive afferents from the thalamus area. These fibers arranged horizontally they are known as Baillarger's external band .

5. Internal pyramidal layer, or ganglion layer

This fifth layer contains a large number of pyramidal cells of medium and large size, as well as Stellate and Martinotti cells . Its horizontally arranged filaments are also part of Baillarger's internal band.

6. Multiform or polymorphic layer

The last of these layers is made up of cells of the fusiform type which derive information from the cortex, the thalamus and the striated nuclei. In addition, it also includes pyramidal cells with a triangular or ovoid body

Your areas and functions

In addition to the types of bark and the layers that comprise it, the cerebral cortex can be divided according to its different functional areas . That is, according to the functions or tasks that are carried out in each of these areas.

Taking this classification into account, the cerebral cortex can be divided into sensory, motor or association areas.

1. Sensitive areas

The sensory area receives the sensory information from concrete nuclei of the thalamus. This information is sensitive , which means that it transports the information perceived by the different senses: sight, hearing, smell, touch, taste ...

This same areas can also be divided into two different sensory areas. The primary sensory area, which has direct connections with peripheral sensory receptors; and the secondary sensory and association areas, which receive sensory information from both the primary association area and the lower brain areas.

The objective of the different association zones, both primary and secondary, is that of create patterns of recognition and behavior through the assimilation of sensory information. These sensitive areas of the cerebral cortex are:

Primary somatosensory area .
Primary visual area.
Primary olfactory area.
Primary auditory area .
Primary gustatory area.

2. Motor area

The areas responsible for the cerebral mechanisms associated with body movement are located in the anterior portion of both hemispheres, that is, in the frontal lobe. In the motor area originate the descending motor treatments that depart from the cerebral cortex towards the motoneuronal trunk and spinal cord.

Within this region we find two essential areas for our operation:

Primary motor area.
Broca's language area.

3. Association area

Finally, the areas of association are those that make possible the existence of more complex and abstract mental functions such as the mechanisms of memory and cognition, the domain of emotions, the ability to reason, and the will. In addition, they also have influence on the development of personality and intelligence.