It is known for a long time that the first signs of Alzheimer’s disease originate in the entorhinal cortex. An area that connects directly with the hippocampus and is key in all processes related to episodic, autobiographical and spatial memory. It is also that structure that protects our identity and the ability to adapt to the environment.
In recent years, advances in neuroscience are encouraging. It is already understood how the TAU protein accumulates in a remarkable way in this region of our brain and thus favors slow neurodegeneration. However, studies like the one published in the Journal of Neuroscience, for example, advance us a really positive data.
It has been seen that the application of electrical stimulation in the entorhinal cortex favors the production of dentate granular cells, which are integrated little by little into the hippocampal networks. That is, neurogenesis occurs, which tends to slightly improve cognitive processes related to memory in these patients.
They are small advances, there is no doubt. However, at present, strategies based on non-invasive brain stimulation are yielding interesting results. Let us know more information about the entorhinal cortex.
“Neuroscience is, by far, the most exciting branch of science, because the brain is the most fascinating object in the universe. Each human brain is different, the brain makes each human being unique and defines who he is.”
-Stanley B. Prusiner-
Functions of the entorhinal cortex
The entorhinal cortex is an area of the brain located in the medial temporal lobe. It is often defined as that “interface” area that works in constant communication with the hippocampus and the neocortex. Also, it should be noted that it is divided into two regions: medial and lateral.
It is, in turn, a structure with multiple connections to different brain areas. It works, for example, in conjunction with the olfactory and visual pathways. It is also linked to the temporal, parietal and frontal lobes. However, as we have already indicated, its main task is to make a direct bridge with the hippocampus.
It is also important to know that interest in the entorhinal cortex arose at the end of the 19th century with Santiago Ramón y Cajal. It was in the middle of his studies to understand the functions of the nervous system when he discovered a peculiar part of the posterior temporal cortex that caught his attention incredibly.
He found the many connections he had with the whole brain fascinating. Let’s see, then, what their functions are.
Declarative and spatial memory
The entorhinal cortex is key to establish two types of memory: declarative and spatial. This means that this constant connection with the hippocampus allows us, among other things, to integrate those events that make up our declarative, episodic and semantic memory. It is in this region where one sculpts, as it were, our identity, internal narrative, our personal history.
At the same time, it also helps us to orient ourselves in the space that surrounds us, to situate ourselves in any scenario.
As we have indicated, the entorhinal cortex sends and receives information to the hippocampus, the most relevant structure of the limbic system. We can not forget that this area is also connected to the amygdala, therefore, it is inevitable that each memory also has an emotional component.
All these processes, integrate and store this small structure so relevant.
The entorhinal cortex integrates various parts of the olfactory cortex. In the animal kingdom, and especially in predators it covers a larger portion, but in humans and primates the olfactory bulb connects only 10% of its structure with the entorhinal cortex.
However, it is usually interpreted that, in our case, this connection facilitates above all that olfactory memory; place where often, we create anchors with certain facts of the past and their particular smells.
The entorhinal cortex and disease
Alterations in the entorhinal cortex are associated with various disorders. The best known is Alzheimer’s disease. Thus, the accumulation of tau protein (mutated), together with the neurofibres that it generates, usually appears especially in this area.
Studies, like the one carried out in the Columbia University Medical Center, by means of functional magnetic resonance, point to this place as the door of this devastating disease. Likewise, it has also been possible to verify how the entorhinal deterioration results in cognitive failures that, little by little, precede the reduction of hippocampal volume. Something very classic in patients with Alzheimer’s dementia.
On the other hand, there is another disease linked to the entorhinal cortex: schizophrenia. Thus, studies like the one carried out at the University of Udine, in Italy, have observed a clear reduction of this area in all patients suffering from this disorder. It appears especially in the right area, forming a very striking structural asymmetry.
The advances in the better understanding of our architecture and brain functionality is undoubtedly a positive fact. Knowing, for example, how to relate these dramatic diseases to areas such as the entorhinal cortex helps us to develop adequate strategies to stop their progress or improve the quality of life of these patients in the future (hopefully) not too far away.