The human brain is not an amorphous and homogeneous mass , but a great number of structures and substructures with great differences between them can be found, which work with different neurotransmitters and which have diverse functions.
While some of these brain structures are known to many people, such as the amygdala or the hippocampus, others are more unfamiliar despite having an important role in regulating our behavior. For example, they help regulate hormones and follow circadian rhythms. This is the case of the epithalamus , which we will discuss in this article.
What is the epithalamus?
The epithalamus is a relatively small structure that is part of the diencephalon and which can be found just above the thalamus and touching the roof of the third ventricle. It is a structure mainly linked to the limbic system, being relevant in the management of instinct and emotions.
It is also associated with the neuroendocrine system through the pineal gland, one of the main structures that forms part of the epithalamus which is also part of this system. This structure has a wide range of connections with the other regions of the brain, including the olfactory system (also related to the perception of and reaction to odours) and many other structures of the brain.
Parts of the epithalamus
The epithelium is made up of a set of structures of great importance to human beings. Apart from the medullary striae, nerve fibres that establish connections with other regions of the brain, we can find two large structures, which are the most relevant and best known of the epithalamus.
Epiphysis or pineal gland
The best known structure of the epithelium is the pineal gland. It is an element known since ancient times (specifically the first information that has been found about it dates from the 3rd century B.C.), Descartes proposed the existence in it of animal spirits related to the emotions.
Inervated by the autonomic nervous system and connected to other nuclei such as the septals, the pineal gland is an important brain structure that regulates the neuroendocrine system , participating in functions such as the regulation of energy and sexuality.
One of the most important aspects of the pineal gland is the fact that it is responsible for secreting melatonin from serotonin, when illumination is non-existent or very low. Thus the epiphysis is essential in the regulation of circadian rhythms and of sleep and wakefulness .
It is also involved in the synthesis of endorphins and sex hormones such as luteinizing hormone, as well as in sexual growth and maturation (which its activity slows down).
Habenula or habenular nuclei
In addition to the pineal gland, the other major structure of the epithelium is the habenula or habenular nuclei (since there are actually two structures). It is linked to the previous one, and it is of great relevance when receiving and sending nucleus connections of the limbic system and the reticular formation . The habenular nuclei are elements that, unlike the epiphysis, do not have endocrine functions.
It acts to a great extent as a bridge between different brain areas (including in addition to the previous ones the thalamic nuclei, those of the prosencephalon or preoptic area) although precisely because of these connections it also seems to be involved in the motivation not to act, the fear and the negative evaluations of events similar to those that could have caused us harm in the past. Finally, they are also linked to the capacity of providing emotional information to smells .
As indicated above, although the epithalamus is not particularly well known, its existence and functioning in the brain is of great relevance to humans, having important functions for our adaptation and survival.
As part of the limbic system, participates in the management of emotion and motivation . In this sense, its role in different disorders such as depression or anticipatory anxiety can be explored.
One of these functions is the management of circadian rhythms, our biological clock that regulates at what times of the day we have and use more or less energy. In this sense it is also very important in the management of sleep, because the pineal gland present in the epithelium reacts to the absence of light by producing melatonin and decreasing energy levels, facilitating sleep.
It also participates in the growth and sexual maturation , adjusting the biological rhythm in which we develop and transform ourselves into adults. Finally, their connections with the olfactory pathways make them relate to the capacity to perceive smells and give them an emotional meaning.
- Kandel, E.R.; Schwartz, J.H. & Jessell, T.M. (2001). Principles of neuroscience. Fourth edition. McGraw-Hill Interamerican. Madrid.