Subcortical Structures Of The Brain: Types And Functions
Absolutely each and every one of our motor, social or emotional abilities and skills are governed and coordinated by 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 the performance of social skills or 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.
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 previously, the subcortical structure is made up of different nuclei, specifically four: the hippocampus, the cerebellum, the amygdala and the basal ganglia, each of them 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 skills in general
Broadly speaking, the main functions in which these brain centers are involved include:
As we mentioned before, Subcortical structures are made up of a series of nuclei, each of which has characteristics that distinguish it and differentiate it from the rest of the centers. Below we will 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), It 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 It plays a fundamental role in memory processes especially in long-term memory, and in spatial navigation.
Lesions in the hippocampus
As mentioned above, this subcortical organ plays a fundamental role in memory processes, so any type of damage or injury to it can cause significant impairment in memory. especially when it comes to 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 area of the cerebral hemispheres. Through three tubes known as cerebellar peduncles, the cerebellum remains connected to the rest of the brain, sending information about body movements
Furthermore, its work in collaboration with the basal ganglia (another subcortical structure) makes the functioning of the sensorimotor system possible.
Broadly speaking, the cerebellum has two primary functions:
In the case of the cerebellum, when it suffers some damage or degeneration, problems begin to appear in motor functions and skills. These problems range from clumsiness in movements or problems accurately controlling their direction and speed, to alterations in coordination, balance and maintenance of a fixed body 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 composed of circuits of neural centers connected to each other which send information continuously and reciprocally.
Furthermore, these centers located at the base of the brain 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 the entire basal ganglia are:
Although each of these centers has a series of its own functions, in general, basal ganglia play a main role in the control and execution of voluntary movements that people carry out unconsciously. That is, it gives us the possibility of carrying out all those routine activities that, although we carry them out voluntarily, we do them “without thinking.”
Lesions in the basal ganglia
As in the rest of the centers of the subcortical system, any type of injury to the basal ganglia will have a direct effect on the functions that they control. In this specific case, Damage to these structures is associated with serious degenerative conditions These pathologies include:
4. Amygdala
Finally, the amygdala is an almond-shaped structure located deep in 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 amygdaloid 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 primary 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 core.
Basal nucleus.
Central core.
Median core.
Intercalated cells.
As with the basal ganglia, although each of these centers has a specific role, all of them are related to feelings and emotions.
At a general level, the amygdala is responsible for emotional control, as well as regulating emotions such as fear and aggressive behavioral responses In the same way, it makes it possible to recognize emotions based on facial expressions and is responsible for emotional memory and pleasure responses.
Amygdala lesions
The abuse of toxic substances, as well as direct damage or injuries to the amygdala, can cause a series of alterations related to emotional management.
A person with some type of damage to the tonsillar body could experience problems in recognizing 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.
