Gray matter of the brain: structure and functions

Almost everyone has heard of gray matter that a person or another has. In Spain, it is a concept that has been popularly associated with intelligence, but in reality its role is much more important than that.

Gray matter can be found in the brain, yesIn addition, its existence is linked to the way in which mental processes related, among other things, to cognition and intelligence develop. But having more or less brainpower does not mean being more or less intelligent. Indeed, its function is more general and essential and concerns the basic functioning of the nervous system.

What is gray matter?

Gray matter, also called gray matter, it includes the areas of the central nervous system in which the sums of neurons predominate (That is, the part of the neuron in which its nucleus is located and its “body” from which the branches leave).

The gray color of these areas contrasts with the white of the rest of the nervous system, which has this aspect because in them the axons of the neurons predominate, that is to say the extensions which arise from the somas and which are covered. by myelin, white.

In qualitative terms, there are no significant differences between the composition of white matter and that of gray matter: in both cases, there are neuronal sums, dendrites and axons with myelin. However, yes there are significant differences in the amounts and proportions in which these elements are present in each of them.

So, technically, gray matter is not part of the brain, but the material with which certain parts of the brain are made.

The distribution of gray matter

The areas of the brain and spinal cord that are made up of gray matter do not form a homogeneous whole, but are distributed and in some cases there is white matter between them. However, in most cases, these areas are large enough that they can be easily seen with the naked eye.

In the spinal cord, gray matter is found in the central and lateral part (In any of its sections, regardless of how high it is), but in the brain it is more distributed.

The cerebral cortex, for example, is made up of gray matterBut the same goes for the basal ganglia, which are located below, with the deepest and most superficial part of the cerebellum, and with many other scattered areas, such as the thalamus and hypothalamus.

The function of these zones

Unlike white matter, in which myelin causes nerve impulses to pass rapidly through axons, gray matter cannot convey information that passes through it so quickly. The main function of these zones is not to pass electricity quicklyBut it has to do with the processing of information, whatever its nature.

The content of the information processed by the gray matter areas being very varied, the effects of a decrease or an increase of this substance are also varied. This is why injuries in these areas depend on the type of structure they affect. However, no part of gray matter can function without the help of white matter, as they must be connected to each other in order to function properly.

As for the gray matter of the spinal cord, it is responsible for acting as an information directoryThat is, it is there that one decides what information goes in and out of the nerves of the peripheral nervous system and what information will have to travel along the spinal cord. In addition, there are some memory theories according to which memories are chemically stored in neural sums, much more abundant in this type of brain tissue.


The presence of gray matter indicates that the part of the brain it is in receives information from many areas of white matter and that, in a way, they function as information processing clusters and in which the nerve impulses traveling through the axons meet with a relief directing them to another destination.

This implies, among other things, that gray matter and white matter are necessary to function as they should; It is not in vain that two types of brain tissue are differentiated by the concentration of the part of the neurons which predominates the most there (axons or somas), and these small nerve cells form an organic unit which cannot be separated without it. destroy.

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