Our central nervous system is made up of two types of tissue: gray matter and what is known as white matter . Gray matter, also called gray matter , is mainly composed of neuronal cell bodies, non-neuronal brain cells (glial cells), and unmyelinated axons, which are processes that extend from neuronal bodies, and are responsible for transporting signals between them. bodies.
Glial cells are of vital importance, since they provide neurons with nutrients and energy. For example, they help transport glucose to the brain, affect the intensity of neuronal communication, and can even cleanse it of excess chemicals.
Gray matter is essential for processing information in the brain . The different structures that we find inside process the various signals generated in the sensory organs, or other areas of the gray matter, directing the sensory stimuli to the nerve cells of the central nervous system, where the synapses induce a response.
These signals reach gray matter through minyelinated axons, which make up most of the white matter in the brain, cerebellum, and spine.
In gray matter, these axons are mainly unmyelinated, which means that they are not covered by myelin , which is a whitish fatty protein. Since these cells do not have white myelin around them (that is, they are not surrounded by it), the matter located in these areas takes on the natural grayish color of glial cells and neurons.
But originally it is not gray. In a living person, its color actually tends to be pinkish brown , mainly because it contains a huge number of tiny blood vessels, known as capillaries.
Therefore, the main difference that we find between white and gray matter is their fat content , since the gray matter is not covered by myelin, which does give that whitish hue to the white matter itself.
And also in your situation: while the white matter is found in the subcortical tissues (the deepest tissues of the brain), the gray matter is mainly found on the brain surface.
The same does not happen with the spinal cord : it has gray matter in its nucleus, and it also has white matter on the outside, with clear insulating and protective properties.
Myelin consists of a fatty substance that surrounds nerve fibers, whose main function is to increase the speed of electrical communication between neurons. It was originally discovered in the mid-19th century (by the German pathologist Rudolf Virchow), although it was almost half a century before scientists discovered its importance as an insulator .
At that moment, Virchow noticed something strange about the nerve fibers that branched out from the spinal cord when he looked at them through the light microscope: they were surrounded by a kind of fatty substance, white in color, and quite shiny.
Later, it was discovered that myelin, composed mainly of lipids and proteins, enveloped the axons of neurons, instead of being inside the nerve fiber (as Virchow did initially believe).
Soon after, in the 1930s and 1940s, scientists discovered that the passage of ions – charged particles – helped maintain the electrical signal, giving them the ability to travel rapidly down an axon.
Thus, in the 1980s, researchers used animal models to evaluate how different electrical nerve signals could be altered after axons were demyelinated. When this happened, the signals tended to move more slowly along the nerve fiber, not even reaching the end of the axon.
These findings were undoubtedly remarkable, because myelin loss is a common problem for many disorders of the central nervous system , including multiple sclerosis, strokes, and spinal cord injuries.
