Habenula: what it is, characteristics and functions in the brain

In this article we will know what the habenula is, and we will see what its parts are, what functions it fulfills, where it is located and what its implications are for human behavior.

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What is habenula?

The habenular nucleus, also called habenula or habenular commissure, turns out to be a brain structure relatively unknown to the population. in general and even for the various health professionals, however, despite the fact that it may be very small, it fulfills very important functions. important. In short, it is about a tiny (half the size of a pea) structure of nerve fibers. The habenula is a tiny (half the size of a pea) region of the brain and is involved in input and output.

On the one hand, it receives input from the brain via the stria medullaris. thalamic and outputs to many areas of the midbrain. Its main functions consist of interconnecting and communicating different nuclei, allowing the passage of information through the components of the thalamus. Therefore, it fulfills

an important role for the communication of the various parts of the brain.

The term habenula is in reference to the elongated shape it presents. From the beginning it was thought that the functions it fulfilled were linked to the regulation of Pineal gland, however, the most current evidence shows that the habenula fulfills the role of a neuroanatomical center that regulates and connects the most important brain regions for motivational states and cognitions to be configured decisions).

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Parts, location and function of the habenula

In the habenula or habenular nuclei it has two parts: the lateral habenular nucleus and the medial habenular nucleus. The habenula turns out to be quite unknown to many people; however, the main function it fulfills is to modulate the different brain structures.

Likewise, it is linked, considering the neurotransmitters it regulates, with gratification, pleasure, cognition, and reinforcement. The most relevant and important function performed by the habenula is to communicate information synapse, which leads to the release of neurological modulators (serotonin, dopamine and norepinephrine). The habenula is located in the epithalamus, specifically inside the diencephalon.

Specifically, it is located in the forebrain with structures such as the thalamus, the pineal gland and the hypothalamus (structures that stand out for their union with the limbic system). It is important to highlight that the habenular nuclei or the habenula is connected to the pineal gland and facilitates the connection between the reticular formation and the limbic system.

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The processes executed by the habenula

The habenula has been linked to the following processes: sleep and wakefulness, reward responses due to its links with the limbic system, sexual behavior, responses behaviors of pain, decision-making (makes us take risks in events in which we express fear) and the evocation of emotions based on smells, since it has afferents olfactory

Effects of alterations in the habenula

The various dysfunctions, conditions and alterations of the habenula reveal the following symptoms: Excessive focus on negative aspects, tendency to show little interest and pleasure in things that are ordinarily pleasurable for any person, hyperarousal in those individuals who present a picture of depression elderly, signs or symptoms similar to those seen in people with ADHD (Attention deficit disorder and hyperactivity). It is important to identify the various negative effects that can be produced in the body by the alterations in the habenula.

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The habenula as a protector of nicotine consumption

Currently, it has been possible to discover the implications of the habenula in the consumption of nicotine. Specifically, the medial habenula circuit protects animals and presumably also humans from consuming high amounts of nicotine.

Medial habenula neurons contain a special type of nicotinic cholinergic receptor. Nerve cells that express these receptors send their axons to the interpeduncular nucleus, located in the midline of the midbrain. This pathway appears to inhibit the reinforcing effects of nicotine.

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Processes in which the habenula is involved

The habenula presents two types of processes, normal and non-normal. within the first has functions related to sleep, sexual behavior, response to reward (due to its links with the limbic system), behavioral response to pain and, among other functions, having a modulating function on various brain structures.

On the other hand, within the non-normal processes it is related to an altered and hyperactive response in people with major depression, lower volume in people oriented to show little interest and pleasure in things ordinarily pleasant. Also, favors excessive focus on negative aspects, is related to behaviors that occur in schizophrenia, and its injury at an early age can reach to generate in the individual symptoms and signs similar to ADHD (Attention Deficit Disorder and hyperactivity).

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Habenula and its relationship with depression

The habenula gives us clues about unpleasant events, according to research carried out by the "University College London" in the United Kingdom. The study was published in "Proceedings of the National Academy of Sciences" and exposes us for the first time that the habenula helps to predict unfavorable or negative events, such as painful electric shocks, suggesting a role in learning from bad or unfavorable experiences.

The research results demonstrate the link between the habenula and motivated behavior as well as show how could be related to the cause of symptoms such as low motivation, pessimism and focus on experiences negative. Finally, understanding the habenula would help us to develop better treatments to deal with depressive symptoms that are often resistant to psychological and medical treatment.

Current studies of the habenula

Today, more in-depth studies are being carried out on the habenula, especially in its possible relationship with drug addiction and the persistence of aversive memories. Similarly, there are works related to depression as discussed above; however, it is still important to continue expanding the research in order to learn more about precision and magnitude the effects that the habenula can have on the integral functioning of our organism. That is why it would be highly recommended to promote research directed towards this field of neurosciences and biological sciences.