4 differences between the GRAY and WHITE SUBSTANCE of the brain

The human nervous system, as a product of its phylogenetic evolution, is a very sophisticated system that has allowed us and allows us to relate to the environment, adapt to it and survive. Important functions such as breathing, physiological activation when danger appears or cognitive functions (such as attention or memory), among others, depend on it.

The complexity of this system means that it still remains a great unknown to science. The nervous system has been the object of study throughout history and, although there are many questions to be resolved in relation to it, we have some knowledge about its operation and structure.

Have you ever wondered what a brain looks like inside? If we could see the brain and / or the spinal cord from the inside, we would realize that there are parts made up of a white color and others made up of a more grayish color. You know why? Keep reading this Psychology-Online article in which we tell you the difference between gray and white matter of the brain.

Index

1. Nerve cells
2. What is gray matter
3. What is white matter
4. Four differences between gray and white matter in the brain

In the nervous system we can find fundamentally two types of cells: neuroglia cells and neurons.

1. Neuroglia cells

Neuroglia cells are made up of oligodendrocytes, astrocytes, ependymal cells, and microglia in the Central Nervous System. These cells do not participate directly in the processing of information but their function is essential for this to occur, since they perform auxiliary tasks and support the function of the neurons.

2. Neurons

The neuron is a nerve cell that represents the basic structural and functional unit of the nervous system and whose function consists of the reception, integration and transmission of information (Crossman, A.R. and Neary, D., 2007). A neuron is made up of:

• A cell body or soma, metabolic center of the neuron that contains both the nucleus and the cytoplasm.
• Call extensions axons (through which nerve impulses are transmitted from the soma) and dendrites (through which nerve impulses are transmitted to the soma).

In this article we talk about the types of neurons, their structure, parts and functions.

The gray matter is the part of the neuronal tissue in which cell bodies or somas are mostly found. The gray matter can be observed, for example, in the cerebral cortex, the cerebellar cortex and part of the spinal cord.

In the following article, you can see the parts of the brain and their functions.

White matter, according to the American Psychiatric Association's dictionary of psychology, refers to the part of the nervous system whose nerve fibers are wrapped in myelin sheaths. What is myelin? Myelin is a substance made up of lipids and proteins that surrounds nerve fibers and whose characteristics are the following:

• The myelination process begins in the second part of pregnancy and continues even after birth.
• The myelination process is linked to cognitive development.
• In the same way, the pathological process of demyelination can cause diseases such as multiple sclerosis.
• They are formed through oligodendrocytes in the central nervous system.
• Peripheral nerve myelin is formed from Schwann cells.
• The coating increases the speed of conduction of action potentials, so that information can be transmitted more quickly.

In the brain hemispheres We find three types of myelinated nerve fibers that make up the white matter:

• Commissural fibers such as the corpus callosum, which mainly connect both hemispheres.
• Association fibers that generally connect different cortical regions of the same hemisphere.
• Projection fibers connecting the cortex and the brainstem.

At this point you will have already been able to observe some differences between both types of substance. However, below, we expose four differences that we can find between gray matter and white matter.

1. Composition

The first and perhaps the most important difference is found in the composition of both substances.

• On the one hand, the white matter It consists mainly of nerve prolongations (mostly axons) that are protected by a myelin sheath.
• On the other, the gray matter It is formed mainly by neuronal bodies or somas.

2. Myelin sheath coating

Another major difference between the two is that:

• While in the white matter we found a myelin coating on the fibers.
• This coating is not found in the gray matter.

This fact causes another of the great differences: its color. The white matter receives its coloration precisely because of the amount of myelin it presents.

3. Distribution in the central nervous system

The crust of the cerebellum it is made up of gray matter. Inside, formed by white matter, we also find masses of gray matter that form the intracerebellar nuclei such as the dentate nucleus, which would be the largest.

In the same way, the cerebral cortex It is also made up of gray matter. His inside It is formed mainly by white matter, although here we also find gray matter nuclei in structures such as the thalamus, the basal nuclei or the striatum, among others.

The spinal cord contains gray matter in the shape of an “H” surrounded by white matter. Following Snell (2003), at a more practical level we can differentiate that in the spinal cord we find:

• Sensory and motor nerve cells that make up the gray matter.
• Ascending and descending tracts that would correspond to the white matter.

4. Related functions

In a simplified way, we can relate, mainly:

• To the regions composed of gray matter with the functions of information processing.
• While the connection functions relate to the parts in which we find the white matter.

This article is merely informative, in Psychology-Online we do not have the power to make a diagnosis or recommend a treatment. We invite you to go to a psychologist to treat your particular case.

If you want to read more articles similar to Difference between gray and white matter of the brain, we recommend that you enter our category of Neuropsychology.

1. Crossman, A.R. and Neary, D. (2007). Neuroanatomy. Text and atlas in color. Barcelona: Elsevier Masson

• Crossman, A.R. and Neary, D. (2007). Neuroanatomy. Text and atlas in color. Barcelona: Elsevier Masson
• Snell, R. (2003). Clinical neuroanatomy. Madrid: Editorial Médica Panamericana.