Hippocampus: functions and structure of the organ of memory
The hippocampus It is one of the most important parts of the brain.
It is located in what is known as the limbic system, and is closely related both to the mental processes related to memory and those that have to do with the production and regulation of emotional states, in addition to intervening in space navigation, that is, , the way in which we imagine movement through a specific space.
The anatomy of the hippocampus
The etymology of the term "hippocampus", a word coined by the anatomist Giulio Cesare Aranzio , refers to the similarity between this structure of the brain with a seahorse. Is about a small organ with a curved and elongated shape, which is located in the inner part of the temporal lobe and it goes from the hypothalamus to the amygdala. Therefore, each encephalon has two hippocampi: one in each hemisphere of the brain.
In addition, the hippocampus is associated with a part of the cerebral cortex known as arquicorteza, which is one of the most ancestral regions of the human brain; that is to say, that appeared many millions of years ago in our evolutionary line. That is why the hippocampus is so well connected to other parts of the limbic system that it appeared to provide answers to some of the most basic needs of our most remote mammalian ancestors. In turn, this fact already allows us to intuit that the mental processes related to emotions are linked to the functions of the hippocampus. Let's see what they are.
The functions of the hippocampus
The main function of the hippocampus is to mediate the generation and recovery of memories in conjunction with many areas scattered along the crust and with other areas of the limbic system.
Therefore, it plays a very important role in the consolidation of the lessons learned, since on the one hand it allows certain information to pass to the long-term memory and on the other it links this type of content with certain positive or negative values, depending on if these memories have been associated with pleasurable or painful experiences (physiologically or psychologically).
Are the mental processes linked to emotion those that determine whether the value of an experience stored as a memory is positive or negative. What we experience as emotions has a functional part that has to do with the way in which we learn to behave according to rules learned that play in our favor: avoid repeating mistakes and re-experiencing pleasant sensations.
The hippocampus and memory
It could be thought that the hippocampus is the part of the brain in which long-term memories are stored . However, reality is more complex than this idea.
The relationship between the hippocampus and long-term memories is not so direct: this organ acts as a mediator, or directory, of memories , whose appearance and disappearance is associated, for what is known about the functioning of memory, to the activation and deactivation of networks of neurons distributed in many areas of the brain. In other words, the hippocampus does not "contain" memories, but acts as an activation node that allows different memories to be activated distributed in different parts of the brain.
In addition, the hippocampus is more related to some types of memory than to others. Specifically, plays a role in the management of declarative memory , that is, the one whose contents can be expressed verbally; However, non-declarative memory, which intervenes in the memorization of movement patterns and motor skills (such as dancing or riding a bicycle), is regulated by structures such as the basal ganglia and the cerebellum.
It is known that a lesion in this area of the brain usually produces anterograde and retrograde amnesia in the production and evocation of memories related to declarative memory, but non-declarative memory is usually preserved. A person with severely damaged hippocampus can continue to learn, for example, manual skills (although he would not remember learning this process).
The hippocampus in space navigation
For what is known about the hippocampus, this brain structure also seems to intervene in the way we perceive space , that is, the way in which we keep in mind a three-dimensional space through which we move, taking into account its volumes and references.
In fact, within the hippocampus have been discovered a type of neurons called place cells, on which you can read more in this article.
The hippocampus under the disease
The region of the hippocampal formation is one of the first areas in which diseases such as dementia or Alzheimer's . That is why people who begin to experience this disease see how their abilities to form new memories or remember more or less recent autobiographical information are diminished.
However, even if the hippocampus is badly damaged, usually the oldest and most relevant memories about the person's life take a long time to disappear , which could mean that with the passage of time the oldest and most relevant memories are increasingly "independent" of the hippocampus.
- López-Pousa S., Vilalta Franch J., Llinàs Reglà J. (2002). Dementias Manual, 2nd Edition. Prous Science, Barcelona.
- Martínez Lage J.M., Láinez Andrés J.M. (2000). Alzheimer's: theory and practice. Medical classroom editions, Madrid.