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Hippocampus and Septum: their relationship with memory and emotions

Hippocampus and Septum: their relationship with memory and emotions

The hippocampus is the main structure of the hippocampal formation or limbic system. Its name in Latin means "seahorse" and is named for its shape.

Content

  • 1 Location of the hippocampus
  • 2 Functions of the Hippocampus: memory and emotional regulation
  • 3 The septum

Hippocampus Location

It is located on the outer wall of the lateral ventricles of the brain and is formed by two twists or folds of the brain and the subicle (sub-curriculum). It communicates with various regions of the cerebral cortex called hippocampal formation, among which are the dentate gyrus, entorhinal cortex and mamillary body.

In the adult brain, neurogenesis (formation of new neurons) occurs in the dentate gyrus, which receives information from other areas of the brain and helps in the memory training and learning.

Ammon's horn is next to the subiculum, and is the main source of the hippocampal formation. The subiculum connects with the para-hippocampal gyrus, a region of the cerebral cortex that surrounds the hippocampus. The para-hypocampic gyrus is in turn involved in the memory storage and recovery.

The hippocampus, through its connections, sends and receives information from areas closely related to the processing of emotional information, such as the amygdala, the prefrontal cortex and / or the cingular cortex.

Functions of the Hippocampus: memory and emotional regulation

One of the most important functions of the hippocampus is the proper functioning of memory, especially with the long-term memory formation. In particular, the hippocampus seems to play an important role in the declarative memory, a type of memory that is responsible for storing information about events, for example names, dates, events, etc. But not only does it help with the storage of these types of memories, but it is also responsible for spatial memory or for the location of objects and people. Without the hippocampus, we couldn't even remember where our house is. It has been shown that Alzheimer disease affects damaging this area of ​​the brain.

Instead the hippocampus is not involved with short-term memory and procedural memory (regulates memories of how to do motor actions, such as walking). These are mainly handled by the cortex and cerebellum.

On the other hand, neurons that continue to be born in the hippocampus during adulthood erase old memories to help form new ones.

It has also been possible to determine that the amygdala is the nexus of functional and anatomical union between the responses and aspects of emotional cognitive processing, and not the hippocampus, as previously thought.

Hippocampal lesions

People who for some reason have lost the function of the main parts of the limbic system, but still maintain those of the hippocampus, they have only long-term memory and are not able to register any new memories or functions.

When both hippocampus are destroyed (right and left), nothing can be retained in memory. The subject quickly forgets any recently received message. The intact hippocampus allows an animal to compare the conditions of a current threat with similar past experiences, allowing it to choose the best option to ensure its own survival.

As we have already mentioned, in Alzheimer's disease one of the first areas that begins to be damaged is the hippocampus. For this reason people who begin to lose your ability to form new memories as well as remember recent information. However, and although the hippocampus is very damaged, it usually takes longer memories to disappear.

The septum

The septal area or septum, is located in the anterior position in the hippocampus, forming the medial wall of the lateral ventricle.

The term septum means septum, and it is an anatomical term used to refer to a partition or division. It is a subcortical structure of the anterior brain that is located near the midline of the brain. The septum in humans can be separated into two structures: the septum pellucidum and the septum verum.

The septum pellucidum, which in Latin means "translucent wall", is a thin and almost transparent membrane that goes from the center of the brain and the corpus callosum to the fornix. Divide the lateral ventricles, forming part of the walls of the anterior region of the lateral ventricles. It consists of a thin structure of two layers of white substance, some neurons, fiber bundles and blood vessels. The septum pellucidum is surrounded by neurons that form the verum septum, which consists of nuclei known as the septal nuclei.

Because of its relationship, anatomically speaking, with structures such as the amygdala, the hypothalamus or the hippocampal formation, the septal area would appear to be a structure related to the neural systems of emotions. But experimental studies only demonstrate small functional relationships with the processing of emotional information.

Septum lesions

Injury to the septal nuclei produces hyperreactivity and an increase in aggressive behaviors. In studies with laboratory rats, it has been found that this effect dissipates two weeks after the injury, at which point the animal becomes very hands and loses its social rank to the group.

The electrical stimulation of the septum produces alterations of certain autonomic responses and the involvement of the septal area in emotions seems to be indirect.

References

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