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 systems.

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

• Related article: "Parts of the human brain (and functions)"

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, the which allows the entire crust to remain in a space as compressed as the interior of the skull. One of these convolutions is the hippocampal gyrus, at whose end 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 of the paleocortex). Despite being part of said cortex, it cannot be seen with the naked eye, since it is largely inserted within the brain.

This hook-shaped structure (the shape being the one that 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) at the head of this organ and with the amygdala (which is partly merged with this structure).

Functions associated with the uncus

This structure plays an important role when it comes to carry out different cognitive processes. The uncus participates and is especially associated with functions related to the limbic system and smell.

1. memory share

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

• Related article: "Types of memory: how does the human brain store memories?"

2. autonoetic consciousness

It is speculated that the uncus and its nerve connections have a high level of relationship with autonoetic consciousness, that is to say, the one through which we build the story of our life, placing ourselves in them.

3. Olfactory information processing

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

4. space navigation

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

5. Mood and anxiety

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

• You may be interested in: "Emotional psychology: main theories of emotion"

Alterations and lesions in the uncus

Although not well known by the majority of the population, the uncus is a part of our body of great importance whose lesion or alteration can generate various symptoms and detrimental effects.

The effects of direct injury to the uncus can cause serious problems with orientation and maintain anterograde memory (that is, the ability to record in our memory declarative information new). Besides it being part of the paleocortex and receiving olfactory information, a lesion in this area can also cause the partial or total loss of capturing smell and aroma.

The uncus can become herniated in such a way that it could 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 lead to hypofunction or even death of part of the brain. The compression of the cranial nerve can generate mydriasis in the same hemisphere in which the lesion or hernia exists, being one of its most evident symptoms on a physical level.

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

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 even a possible alteration in this area has been investigated in subjects psychopaths.

• Related article: "The 15 most frequent neurological disorders"

Bibliographic references:

• Craig, M.C.; Catani, C.; Deeley, Q.; Latham, R.; Daly, E.; Kanaan, R.; Picchioni, M.; McGuire, P.K.; Fahy, T. & Murphy, D.G.M (2009). "Altered connections on the road to psychopathy". Molecular Psychiatry. 14 (10): 946–53, 907.

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

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

• Redolar, D.; Moreno, A.; Robles, N.; Soriano, C.; Torras, M.; Ok, A.M. (2010). Fundamentals of psychobiology. Editorial UOC. Barcelona.