The insula: anatomy and functions of this part of the brain
By now it is known to the vast majority of the population that the human brain is divided into four brain lobes.
With a simple picture of the brain we would be able to locate a large number of parts of the brain. However, there is a very relevant structure that can remain hidden from visual observation, taking into account that it is located at a certain depth behind one of the main furrows of the brain. This structure is called the insula.
What is the insula?
Also considered as the fifth cerebral lobe, the insula is a structure of the cerebral cortex located in the depth of the Silvio fissure, at the point where the lobes converge temporary, parietal Y frontal, being delimited by their respective covers.
The insula is part of the mescortex, or paralimbic system, along with the orbitofrontal and other structures. It is a connection center between limbic system and the neocortex, participating in very diverse functions, either directly or indirectly.
A part of the cerebral cortex
Being clear about what the cerebral cortex consists of can help to understand the type of processes that take place in the insula.
The cortex of the brain, of which the insula is a part, is the rough part that extends over most of the outside of the brain. However, as we have seen, it is not defined by being on the outside and totally exposed to observation, since the insula is hidden and the brain has to be manipulated to see it. However, the reason why it is in the superficial part of the Central Nervous System is the same for the that the rest of the cortex is arranged in this way: the need to accumulate gray matter in areas strategic.
Gray matter is made up of neuronal bodies, which are the parts of neurons in which the nucleus is located and in which the most important processes of nerve transmission take place. They receive information from other parts of the nervous system, and at the same time send information to others.
But to centralize all these tasks, space is needed, and that is why the cerebral cortex exists: its rough and folds are made to be able to concentrate the greatest amount on it. possible amount of gray matter, in an almost unbroken continuum along the outer surface (and not so outer, depending on how deep the folds and fissures are) of the brain.
A) Yes, both the insula and the rest of the lobes of the brain are not passage areas for nerve impulses, but regions in which complex psychological processes take place and in which information from very diverse areas of the nervous system is integrated.
Insula Components
The insula is not only a uniform structure that performs the same functions in a homogeneous way, but also different parts of this structure take care of various tasks. Specifically, the insula is divided into anterior and posterior insula, both parts separated by the central insular groove.
The posterior region of the insula is mainly innervated with somatosensory neurons, which are those that create a "map" of the sensations of position related to the different parts of the Body. with which the participation of this region will be linked more with control of the viscera and internal organs.
The anterior part of this brain structure is more closely related to the limbic system, its functionality more oriented to the emotional integration of experiences and perceptions as a unitary sensation and global.
Main functions of the insula
Let's look at some of the main functions of the island region.
As we have seen, the insula influences a large number of basic and higher processes (related to thought decision-making), and is an element of great importance for the proper functioning and even survival of the organism. In this sense, the research carried out in the field of neurosciences shows that the insula participates in the following processes.
1. Taste and smell perception
The sense of taste has its main primary sensory area at the lower end of the insula. and in the parietal cortex. It is at this point where the gustatory information becomes conscious, appearing as a private and subjective experience but related to the elements of the environment that we savor.
It has also been observed that the insula participates in the perception of the smell, although this sense tends to have a dispersed neural network throughout the brain.
2. Visceral control and somatoperception
The insula also has an important role in the regulation of the viscera and organs. Specifically, it has been observed that its experimental manipulation produces important variations in blood pressure and heart rate. It also participates in the sensations coming from the digestive system, also participating in the management of this system and the respiratory system.
3. Vestibular function
Vestibular function, which refers to body balance and control of the body in relation to space, also presents references to the insular region, being a relevant nucleus in their conscious perception. Thus, thanks to the insula, a healthy person is able to know what position each of the main parts of his body occupies at all times.
4. Integration of emotional and perceptual information
The insula, as mentioned above, acts as an association zone between very different observations, especially with regard to the association between perception and emotion.
So, thanks in part to this brain region we learn from our experiences, since we link pleasant subjective sensations or unpleasant to what we do and say and, in this way, we associate behaviors with consequences through what we perceive.
5. Involvement in addictions: desires and craving
Due to its relationship and its connections with the limbic system, the linkage of the insula with the brain reward system has been explored. The investigations carried out have shown that this structure intervenes in the processes of addiction to certain drugs, helping to maintain addictive behavior.
This relationship is due to the involvement of the insular region with the integration between emotion and cognition, being involved especially in the phenomenon of craving or intense desire for consumption.
6. Empathy and emotional recognition
We have seen earlier that the insula has great connections to the limbic system. In this regard, recent research has indicated that this region of the cerebral cortex plays a key role in the ability to recognize emotions and of the empathy. Thus, it has been shown that those individuals without an insula present a much lower recognition, especially with regard to the emotions of joy and surprise, as well as pain.
In fact, it has been suggested that the deficits found are very similar to some cases of autism, Borderline personality disorder and behavior problems, with which research could be carried out regarding the functioning of this brain area in certain disorders.
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