Glial Cells: The Basis Of Brain Function

The brain is one of the most important organs in the body. It allows us to talk, move, feel and think. Due to this key role , a lot of research has been done focusing on brain function. This is to understand the different parts that form the brain and the way it works.

Neurons were originally thought to be the only cells responsible for brain activity. Recent research, however, has highlighted the role glial cells play in brain function. As studies now show, glial cells are fundamental players in the transmission of information. As recent studies show, some of the most important brain diseases are not just related to neuronal damage. Glia cells also deteriorate as a result of brain disease.

Brain function: What are glial cells?

You will be able to understand the importance of these small cells just by looking at one example. During many different experiments, attempts were made to keep neurons isolated in containers, but they always died within a few days. Later, researchers found that if they added an extract from the glial cells, they could control the death or survival of the neurons, which highlighted the key role of glial cells in neuronal survival.

As studies have found, we have a very large amount of glial cells or neuroglia . The name comes from the Greek word “glia” which means “glue” plus “neuro”, a term related to the brain. In other words, glial cells are glued to our brain.

Traditionally, glial cells have been considered to have a very passive role in the brain, acting only as metabolic, structural and trophic support for neurons. Recent research shows, however, that they have many more functions in different processes that take place in the brain. They often enable the work of other types of neurons.

Functions of glial cells

Glial cells have several functions. Some of them are the following:

• Insulation. Glial cells produce a substance called myelin, which is important for isolating neurons. This dense fabric is designed to cover the axons, protect cells and allow the information transfer to be fast and efficient. In the same way, it helps prevent messages from neurons from mixing up. In addition, it has a key role in learning. As studies show, the amount of myelin in our brain increases when learning processes take place.
• Source of nutrients. As we know, the neurons in the brain use a good amount of energy. Although they have some nutrient reserves, these are not enough to maintain brain activity beyond a few minutes. In this way, glial cells help to provide nutrients and energy that the neurons lack. They do this by incorporating energy molecules such as glucose, which they get from the blood.

• Cleansing. Glial cells help remove waste products related to neuronal function. They do this in two ways. First, by removing some of the neurotransmitters that remain in the synaptic space, and then transforming them and returning them to the original neuron so that they can once again become raw material for new neurotransmitters. Second, they are responsible for eliminating the remnants of dead neurons. This is especially important when there is damage to the nervous system. Furthermore, this cleansing action helps to mitigate the chemical and physical effects that these residues can generate.
• Improvement of synapse. The presence of these cells helps to release thrombospondin, which facilitates synapses and in turn increases synaptic activity.

Brain function: Types of glial cells

There are different types of glial cells, each of which performs a number of different functions. They all play an important role in neuron and brain function.

There are different ways to classify glial cells. One way to do this is by looking at the location of the nervous system. This is what we will take into account to explain each type.

Central nervous system

First, there are astrocytes. These are large, star-shaped glial cells, which is why they are referred to as   macroglia (large glial cells). These are the most common glial cells in the brain. In terms of location, they surround the synaptic connections in the brain.

One of the main functions is to define cellular boundaries and contribute to the formation of a defensive barrier for the brain. They also control the formation and functionality of synapse, neurogenesis and regulation of muscle tone. On the other hand, they help feed neurons.

There are also oligodendrocytes. This is macroglia in the central nervous system. By giving myelin cell axons, they are the key to cell isolation. These cells have the capacity to transmit myelin to more than one neuron and can in some cases help to regenerate damaged axons.

Finally, there is microglia, which helps in the brain’s cleansing processes. They respond when there is damage to the system, clear cellular debris and trigger the brain’s inflammatory response.

The Peripheral Nervous System (PNS)

In this part of the nervous system, the Schwann cells take over, which is macroglia. These glial cells are divided into three subtypes. The first is the type that forms myelin. As the name suggests, it helps to give myelin to the axons, but they can only do so with one axon at a time. In case of brain damage, they fulfill the function of cleansing and favoring the conditions for regeneration.

Second, it is Schwann cells that do not form myelin. The manner in which these cells communicate with the axons is currently unknown. Nevertheless, studies show that they are necessary for the function and maintenance of axons without added myelin, which are essential for generating the feeling of pain.

Third, there are the perisynaptic Schwann cells. These cells cover the neuromuscular compounds and release neurotransmitters and peptides. The receptors located in the membrane allow them to generate signals related to these substances. In the same way, they can control and potentiate synapses.

In short, glial cells are a fundamental part of the nervous system and brain function. Not only do they support the cells, but they also help with activities such as synapses, cleansing and nutrient generation. Therefore, they have an important influence on the development of some diseases, such as multiple sclerosis.