Subiculum: Parts And Functions Of This Brain Structure
The hippocampus is one of the oldest parts of the brain; It is believed to have been working in our ancestors for hundreds of millions of years. It is a biological structure known to be closely involved in the functioning of memory. Our own individual identity, as well as our ability to learn, depends on it.
The hippocampal formation, which is the region formed by the hippocampus and a series of adjacent structures, is not functionally homogeneous; It has several parts that deal with different things. The subiculum is one of them and has a very special role in the functioning of memory, as has been recently discovered.
The subiculum is a part of the brain located at the bottom of the hippocampal formation, one of the latter existing in each of the cerebral hemispheres. It is formed mainly by gray matter, since in this anatomical region the somata of neurons that connect with neural structures such as the amygdala or the hypothalamus are grouped.
Its functions
Although not much is known about the exact function of the subiculum, it is generally associated with two functions: the memory system’s own processing of memories which involves different parts of the brain, and the processing of spatial and movement information, related to the space that objects occupy at a given moment. In addition, it is believed to have an important role in epileptic seizures.
Until a few years ago, it was believed that human memory worked in the following way. When experiencing an experience, a representation of it is “recorded” by the networks of neurons that make up the hippocampus. This brain structure would be responsible for making short-term memory processing of this experience possible; That is, when we remembered that information minutes, hours or a few days after having memorized it, the hippocampus would be the part of the brain that retrieves data
However, over time this memory passes from short-term memory to long-term memory, and with this transition there would also come a “migration” of the data stored in the brain: they would move from the hippocampus to other parts of the brain, distributed between the frontal, temporal and parietal lobes of each hemisphere.
However, a few years ago it was discovered that this is not how memory works, and that the subiculum plays a very important role in it.
The subiculum as a short-term memory store
As recent studies carried out with techniques to illuminate in real time the most activated parts of the brain at each moment have shown, when we live a new experience, its memory passes from the hippocampus to two parts of the brain. It is “archived” in two copies that operate in parallel, with relative independence from each other. The short-term memory is stored in the subiculum and the long-term memory remains in the cortex of the frontal lobe, but remains “deactivated”, latent.
At first, it is the copy of the memory stored in the subiculum that makes us able to recall those experiences shortly after having lived them. However, as the days go by, this copy disappears, and the memory stored in the front part of the brain cortex becomes activated.
So, this process establishes that the functioning of memory processing follows two different routes, instead of following a sequence in which the memory physically travels from one specific place in the brain to another. There is a part of the memory that remains silent and that, only if certain conditions are met, does it manifest.
Parts of the subiculum
The subiculum can be divided into several structures They are the following.
1. Presubiculum
This is the area through which information from the hippocampus enters. This linked to memory and movement processing
2. Postsubiculum
This part of the subiculum contains neurons responsible for keeping the face focused in a certain direction allowing its location to correspond to certain objectives.
3. Parasubiculum
This part of the brain contains network cells, which are neurons that activate when we perceive certain movements and register them as such.
4. Prosubiculum
Little is known about this region, although it has been seen that it may play a role in the appearance of anosognosia. in cases of Alzheimer’s disease Furthermore, in this area of the brain the neurons are somewhat smaller and are distributed in a more compact and dense formation than in most other similar regions.
