The cerebral cortex is one of the most well-known, developed and visible structures in our brain, possessing a large number of functions that enable us to be who and how we are and to behave adaptively in order to survive. But it’s not a homogeneous mass that takes care of everything: different regions of the brain have different nerve fibers that specialize in different functions.
While it is common to know names such as prefrontal or orbitofrontal cortex, other areas are not as popular and tend to go more unnoticed despite performing important functions. Among these, we find the entorhinal cortex, Which we will talk about in this article.
What is the entorhinal cortex?
The entorhinal cortex is a region of the brain located in the ventromedial temporal bone, specifically located in full-form parahippocampal convolution in the olfactory crust of the uncus and in direct contact with the hippocampus. It includes Brodmann zones 28 and 34 and is bordered by the peririnal cortex and the lateral sulcus.
This region of the brain has multiple connections with different areas of the brain. It connects to the olfactory and visual pathways and to the different structures of the temporal, parietal and frontal lobes (Comprising the orbitofrontal crust. Yet the structure with which a greater level of connection possesses is the hippocampus, serving as a center of relief that distributes the information that enters or leaves it and acts as a bridge between it and other areas of the brain between the hippocampus and the entorhinal cortex is achieved by what is called the perforation pathway.
It is considered to be a zone of association that comes to integrate and send information to the hippocampus, as well as a relevant part of the limbic system, receiving afferents from the amygdala and helping to provide sensory information with emotional components in memory.
The entorhinal cortex plays a very important role in our body, allowing the achievement, integration and proper functioning of a large number of cognitive functions. Some of the functions in which this part of the crust has been most involved are as follows.
1. Rescue center
Traditionally its best known function, one of the multiple roles of the entorhinal cortex is that of allow information from the rest of the crust to reach the hippocampus and in turn, what comes from the hippocampus reaches the rest of the brain.
2. Memory: formation and consolidation of memories
The entorhinal cortex is considered to be one of the most important brain nuclei in terms of memory capacity, being the bridge through which information arrives and is sent to or from the hippocampus.
This is a key region in the formation and consolidation of memoryIn fact, injury to the entorhinal cortex can make it difficult, if not 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, which is linked to its role in consolidating memories in memory.
The entorhinal cortex is not only important in forming memories, but also in recognition of stimuli. And it’s deeply tied to semantic memory, which dictates what we see and allows us to recognize them.
4. Association of visual and auditory information
This brain region also plays an important role at the associative level, being an area in which auditory and visual information is integrated. In fact, information referring to all the senses passes through the entorhinal cortex, although this information comes directly from multimodal partnership areas (That is, not only the information of one sense arrives but directly the integration of several).
5. Space navigation
Another function in which the involvement of the entorhinal cortex is observed is spatial orientation and navigation. This zone is what this lets us know in which direction we are heading, Be involved in the formation of mind maps.
6. Odor coding
The entorhinal cortex also plays an important role vis-à-vis the olfactory system. More precisely, has been associated with the ability to encode odor intensity and in the association of smells with memories.
Certain associated disorders
The entorhinal cortex is an important region of the brain where injury can have multiple consequences and effects. It mainly occurs with impaired memory and recognitionBut there are also difficulties in terms of orientation, visual and motor problems.
Among some of the major disorders in which the existence of lesions of the entorhinal cortex has been observed (usually joined to those of the hippocampus), we can list the following.
1. Amnesic syndrome
Amnesia syndrome is understood as memory impairment resulting from a certain type of brain injury (psychogenic amnesias or those caused by nonorganic mental disorders are not included in the syndrome).
In amnesic syndrome anterograde amnesia mainly occurs in which the subject is unable to register new information, which 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 also a significant involvement of the entorhinal and perirhinal cortex.
Many authors and researchers consider that the entorhinal cortex is one of the points of origin of Alzheimer’s disease, being one of the first areas affected by this disease. More precisely, neurodegeneration generated by the accumulation of tau proteins is observed on the lateral part of the entorhinal cortex, as well as the formation of beta-amyloid plaques. This will then extend along the temporal cortex and eventually to the rest of the brain as the disease progresses.
While this is not a disorder per se but rather 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 complicate this process, as it binds to hippocampal memory. For example, odor recognition may disappear.
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