Subcortical Structures Of The Brain: Types And Functions

We explain to you how are the nuclei of nerve cells that are hidden under the brain surface.

Brain

Absolutely each and every one of our motor, social or emotional capacities and abilities are governed and coordinated from the various structures that make up the entire brain.

One of these systems are the subcortical structures of the brain, which have functions in the motor system, such as in the performance of social skills or in the regulation of emotions. Throughout this article we will explain each of these structures as well as the possible consequences of an injury to them.

What are subcortical structures?

Within the field of neuroanatomy, the structures that make up the nervous system are studied. Some of these systems are those known as the subcortical structures.

The subcortical system or structure, located in both cerebral hemispheres, is composed of those brain centers that are located between the white matter, located near the lateral and ventral region of the lateral ventricles.

As complementary information, white matter is the matter that makes up 60% of the brain. This substance is made up of a large number of nerve fibers, which in turn contain neuronal axons. These axons are characterized by being covered by a myelin sheath that protects them and favors the rapid transmission of nerve electrical signals.

As mentioned above, the subcortical structure is made up of different nuclei, specifically four: the hippocampus, the cerebellum, the amygdala and the basal ganglia, each with a specific location and functions, so in case of injury the person will experience a significant decrease in a whole series of psychological and mental abilities and abilities in general.

Broadly speaking, the main functions in which these brain centers are involved include:

  • Regulation of character and emotional responses.
  • Regulation of the instinctual responses of the person: flight response, hunger, etc.
  • Modulation of the visceral and endocrine functions of the organism.
  • Regulation of the processes of wakefulness and sleep.
  • Regulation of attention and arousal processes.

Subcortical brain centers

As we mentioned earlier, subcortical structures are made up of a series of nuclei, each of which has characteristics that distinguish it and differentiate it from other centers. We will now describe them one by one, as well as their functions and the consequences that may appear if they are injured.

1. Hippocampus

The hippocampus is one of the main brain structures that can be found in both humans and other mammalian animals. This small organ located in the intermediate temporal lobe and with a shape that resembles that of a seahorse (hence the etymological origin of its name), is one of the most important parts of the limbic system.

Traditionally, the limbic system has been associated with the regulation of emotions, while the hippocampus plays a fundamental role in memory processes, especially long-term memory, and in spatial navigation.

Hippocampal injuries

As mentioned above, this subcortical organ plays a fundamental role in memory processes, so any type of damage or injury to it can significantly impair memory, especially when generating new memories.

For example, in Alzheimer’s disease, hippocampal damage caused by neurodegeneration is one of the first symptoms to appear, initially causing disorientation and mild memory problems.

2. Cerebellum

This second region belonging to the subcortical structure and known as the cerebellum is located in the lower zone of the cerebral hemispheres. Through three channels known as cerebellar peduncles, the cerebellum remains connected to the rest of the brain, sending information about body movements.

In addition, his work in collaboration with the basal ganglia (another of the subcortical structures), makes possible the functioning of the sensorimotor system.

Broadly speaking, the cerebellum has two primary functions:

  • Development of motor learning and control of movements acquired through the creation of neural patterns that turn them into mechanized movements.
  • Correction of errors in movement through feedback.

Lesions in cerebellum

In the case of the cerebellum, when it suffers some damage or degeneration, problems in motor functions and skills begin to appear. These problems range from clumsiness in the movements or problems to control with precision the direction and the speed of these, to alterations in the coordination, the balance and maintenance of a fixed corporal posture.

Damage to the cerebellum can be caused by diseases such as multiple sclerosis, endocrine system disorders, spongiform encephalopathies, or chronic alcoholism.

3. Basal ganglia

The brain organization known as the basal ganglia is made up of interconnected circuits of neural centers, which send information to each other continuously.

In addition, these centers located in the brain base have the ability to unite the lower regions of the brain, such as the trunk and spinal cord, with the higher ones located in the cerebral cortex.

The different centers that make up all of the basal ganglia are:

  • Pale balloon.
  • Nucleus accumbens.
  • Caudate nucleus.
  • Putamen.
  • Lenticular nucleus.
  • Striated body and neostriated body.
  • Black substance.

Although each of these centers has a series of its own functions, in general, basal ganglia have a main role in the control and execution of voluntary movements that people carry out unconsciously. In other words, it gives us the possibility of carrying out all those routine activities that, although we do them voluntarily, we do them “without thinking.”

Basal ganglia injuries

As in the rest of the centers of the subcortical system, any type of lesion in the basal ganglia will have a direct effect on the functions that they control. In this specific case, the damage to these structures is associated with serious degenerative conditions. These pathologies include:

  • Cerebral palsy.
  • Huntington’s disease.
  • Parkinson’s disease.
  • PAP syndrome.

4. Amygdala

Finally, the amygdala is an almond-like structure located deep within the temporal lobes. Like many other subcortical structures, the amygdala is made up of a series of neuronal centers which have their own functions.

Also known as the tonsillar body, it is one of the structures that generates the most interest in the field of psychology, since its condition as a deep brain makes it the main regulator of our most basic emotions, as well as our most primal survival instincts. .

Taking this information into account, we can affirm that both in people and in other vertebrate animals, the amygdala constitutes one of the cornerstones of the evolution of species.

The neural centers that make up the amygdala are:

  • Lateral nucleus.
  • Basal nucleus.
  • Central core.
  • Middle core.
  • Intercalated cells.

As with the basal ganglia, although each of these centers has a specific role, they are all related to feelings and emotions.

At a general level, the amygdala is responsible for emotional control, as well as the regulation of emotions such as fear and aggressive behavioral responses. In the same way, it enables the recognition of emotions according to facial expressions and takes care of emotional memory and pleasure responses.

Injury to the tonsil

The abuse of toxic substances, as well as direct damage or injury to the amygdala can cause a series of alterations related to the management of emotional ones.

A person with some type of deterioration in the tonsillar body could experience problems in the recognition of facial expressions that reflect emotions. Another consequence is the lack of response to sexual stimuli or the inability to recognize one’s own feelings of love, happiness, anguish or anger among many others.

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