Entorhinal cortex (brain): what is it and what functions does it have?

The cerebral cortex is one of the best known, developed and visible structures of our brain, possessing a large number of functions that allow us to be who and as we are and behave adaptively for that survive. But we are not dealing with a homogeneous mass that takes care of everything: different brain regions have different nerve fibers that specialize in different functions.

Although it is common to know names such as the prefrontal or orbitofrontal cortex, other areas are not as popular and tend to go unnoticed despite carrying out important functions. Among the latter we can find the entorhinal cortex, which we are going to talk about in this article.

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What is the entorhinal cortex?

The entorhinal cortex is a region of the brain located in the ventromedial temporal, specifically located in the parahippocampal gyrus caudal to the olfactory cortex of the uncus and in direct contact with hippocampus. It includes Brodmann's areas 28 and 34, and borders the perirhinal cortex and lateral sulcus.

This brain region has multiple connections with different areas of the brain. It connects with the olfactory and visual pathways and with different structures of the temporal, parietal, and frontal lobes. (including the orbitofrontal cortex. However, the structure with which it has the highest level of connection is the hippocampus, serving as the center of relay that distributes the information that enters or leaves it and acting as a bridge between it and other areas of the brain. The connection between the hippocampus and the entorhinal cortex is carried out through what is known as the perforating pathway.

It is considered an association area that ends up integrating and sending information to the hippocampus, as well as a relevant part of the limbic system, receiving afferents from the amygdala and contributing to endow sensory information with emotional components in memory.

Principal functions

The entorhinal cortex plays a very important role in our body, allowing the realization, integration and proper functioning of a large number of cognitive functions. Some of the functions in which this part of the cortex has been most involved are the following.

1. relay center

Traditionally its best known function, one of the many roles of the entorhinal cortex is that of allow information from the rest of the cortex to reach the hippocampus and in turn that which arises from the hippocampus reaches the rest of the brain.

2. Memory: formation and consolidation of memories

The entorhinal cortex is considered one of the most important cerebral nuclei with regard to the memory capacity, being the bridge through which information arrives and is sent to or from the hippocampus.

Is about a fundamental region in the formation and consolidation of memoriesIn fact, damage to the entorhinal cortex can make it difficult or even impossible to encode and record new content or information, producing anterograde amnesia.

One aspect to note is that this cortex is active during sleep, especially in REM sleep, something linked to its role in consolidating memories in memory.

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3. gnosis

The entorhinal cortex is not only important in memory formation, but also in recognition of stimuli. And it is that it is deeply linked to semantic memory, which tells us what the things we see are and allows us to recognize them.

4. association of visual and auditory information

This brain region also has an important role at the associative level, being an area in which auditory and visual information is integrated. Information pertaining to all the senses actually passes through the entorhinal cortex, although such information arrives directly from multimodal partnership areas (that is, that information from one direction does not arrive only, but rather the integration of several directly).

5. space navigation

Another of the functions in which the involvement of the entorhinal cortex has been observed is orientation and spatial navigation. This area is the one allows us to know in which direction we are moving, being involved in the formation of mental maps.

6. odor coding

The entorhinal cortex also has an important role in what refers to the olfactory system. Specifically, has been associated with the ability to encode the intensity of odor and in the association of smells with memories.

Some associated disorders

The entorhinal cortex is an important brain region whose damage can have multiple consequences and effects. Mainly memory and recognition alterations occur, but there are also difficulties at the level of orientation, visual and motor problems.

Among some of the main disorders in which the existence of lesions in the entorhinal cortex (generally joint with those of the hippocampus) has been seen, we can list the following.

1. amnesic syndrome

Amnesic syndrome is understood to be that alteration of memory derived from some type of injury brain (psychogenic amnesia or amnesia produced by non-psychic mental disorders are not included in the syndrome). organic).

In the amnesic syndrome anterograde amnesia occurs fundamentally in which the subject is unable to record new information, something that may or may not be accompanied by retrograde amnesia (no recollection of previous events in the subject's life). Traditionally linked to hippocampal problems, in this type of syndrome there is usually also significant involvement of the entorhinal and perirhinal cortex.

2. Alzheimer's

Multiple authors and researchers consider that the entorhinal cortex is one of the points in which originates Alzheimer's, being one of the first areas that are affected by this disease. Specifically, neurodegeneration generated by the accumulation of tau protein is observed in the lateral part of the entorhinal cortex, as well as the formation of beta-amyloid plaques. This will subsequently spread throughout the temporal cortex and finally to the rest of the brain as the disease progresses.

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3. Agnosias

Although we are not dealing with a disorder in itself but rather with a symptom, agnosia is understood as the lack of recognition of the properties of a stimulus with which we are familiar. The presence of lesions in the entorhinal cortex can hinder this process, as it is linked to hippocampal memory. For example, odor recognition may disappear.