Uncus: Structure and Functions of This Part of the Brain

The brain is, as we already know, one of the most important organs for our survival. The main organ of the nervous system governs and modulates the functioning of the rest of the body’s systems.

But it is not a simple uniform mass of neuronal tissue, but rather it consists of different structures that can be divided into different parts, the most superior and external being the cerebral cortex. One of the structures that are part of the cerebral cortex is the uncus , which is also linked to the limbic system. We will talk about this structure of the nervous system in this article.

Table of Contents

Uncus: definition and location of this structure

If we look at the cerebral cortex we can see a large number of small gyri and sulci, which allows the entire cortex to remain in a space as compressed as the inside of the skull. One of these gyri is the hippocampal gyrus, at the end of which we can find the uncus.

The uncus is then one end of the parahippocampal gyrus or hippocampal gyrus, being part of the cortex of the temporal lobe of the brain (specifically the paleocortex). Despite being part of said cortex, it cannot be observed with the naked eye, since it is largely inserted within the brain.

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This hook-shaped structure (the shape being what gives it its name) It is also part of the limbic system connecting with the hippocampus (some authors even consider it part of the hippocampal formation) in the head of this organ and with the amygdala (which partially fuses with this structure).

Functions associated with the uncus

This structure has a relevant role when it comes to carry out different cognitive processes The uncus participates and would be especially associated with functions related to the limbic system and smell.

1. Participation in memory

One of its main functions is to participate in the encoding of working memory and to contribute to its consolidation. Furthermore, it has been observed that it contributes to record new information in the form of memories being involved in anterograde memory.

2. Autonoetic consciousness

It is speculated that the uncus and its nervous connections have a high level of relationship with autonoetic consciousness, that is, the one through which we construct the history of our life by placing ourselves in them.

3. Processing of olfactory information

Another of its functions is linked to the olfactory system, processing its information and transmitting its information. Hyperstimulation of the uncus It can cause the existence of olfactory hallucinations. It is also responsible for the fact that strange olfactory sensations may arise before or during an epileptic seizure.

4. Space navigation

Finally, it is also related to navigation in space, contributing to the formation of brain maps and the ability to orient yourself.

5. Mood and anxiety

The fact that it is connected to the limbic system means that the uncus is related to the regulation of mood and anxiety, There may be alterations linked to these elements if it looks damaged.

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Alterations and injuries in the uncus

Although not well known by the majority of the population, the uncus is a very important part of our body. whose injury or alteration can generate various symptoms and harmful effects.

The effects of a direct injury to the uncus can cause serious problems when it comes to orientation and maintaining anterograde memory (that is, the ability to record new declarative information in our memory). In addition to that being part of the paleocortex and receiving olfactory information, an injury to this area can also cause partial or total loss of capturing odor and aroma.

The uncus can herniate in such a way that it can pinch and compress the third cranial nerve (the oculomotor nerve), the cerebral aqueduct, the posterior cerebral artery or/and the third cranial nerve. This would produce various effects of varying severity.

One of the possible consequences is the generation of a cerebral stroke in the event that the posterior cerebral artery is compressed, which could cause hypofunction or even death of part of the brain Compression of the cranial nerve can generate mydriasis in the same hemisphere in which the injury or hernia exists, being one of its most obvious symptoms on a physical level.

However, if what is compressed is the midbrain, loss or alterations of consciousness, hemiparesis may appear, and we could even be facing an injury with the potential to cause brain death in the affected individual.

Relationship with various mental disorders

Some symptoms of various neurological mental disorders to alteration of the uncus It has been linked to anxiety and mood disorders, schizophrenia, various types of brain injuries and poisoning, or a possible alteration in this area has even been investigated in psychopathic subjects.

Kandel, E.R.; Schwartz, J.H.; Jessell, T. M. (2001). Principles of Neuroscience. Madrid: MacGrawHill.

Madrigal, E. and Hernández, C. (2017). Generalities of Brain Trauma in Legal Medicine. Bibliographic review. Legal Medicine of Costa Rica 34 (1). Costa Rica.