The brain continues to be a great mystery for neuroscience, although we can increasingly shed a little more light on this complex structure that allows us to feel, emote and think.
One of the brain structures widely studied has been the hippocampus, a structure located in the limbic system, closely related to memory and the link between emotions and memories. However, among its functions others have also been found, such as the .
What else do we know about this structure? In this article we will talk about its anatomy, location, functions and alterations in case of suffering an injury to the hippocampus.
What is the hippocampus and where is it located?
The hippocampus is a very important brain structure, involved in memory and other psychological processes such as . It is located, as we will see later, in the inner part of the temporal lobe, a large structure located on the lower side of the brain, closely related to hearing and other processes.
Thus, we know that the emotional processes linked to emotions are another aspect related to the hippocampus, a structure that is located in the limbic system.
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Limbic system
The limbic system is made up of different structures at the brain level, responsible for regulating physiological responses to certain stimuli. It is in the limbic system where human instincts are “found”, such as: hunger, sexual instincts… This system is also responsible for regulating involuntary or unconscious memory, attention, emotions, personality or behavior. .
Returning to the hippocampus, this term was coined by , a leading figure in the history of the science of human anatomy. With this term Aranzio wanted to refer to the similarity between this structure of the brain and the silhouette or shape of a seahorse.
hippocampus anatomy
Thus, at an anatomical level, the hippocampus is a small organ with a curved and elongated shape, located in the inner part of the temporal lobe. It is articulated from the hypothalamus to the amygdala. In this way, we find that each brain has two hippocampi, one for each cerebral hemisphere (the left and the right).
This structure is associated with a part of the cerebral cortex called the archicortex. The archicortex is one of the most ancestral regions of our brain, since it appeared millions of years ago in our evolutionary line as a species.
For this reason, the hippocampus is connected to other areas of the limbic system. For its part, the limbic system was defined, at an evolutionary level, so that our ancestors responded to their most basic needs.
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Functions of the hippocampus
The hippocampus is involved in memory, in the production and regulation of emotional states and in spatial navigation, this being understood as the way in which we imagine movement in a certain space.
We can say that its main function is related to mediating the generation and recovery of memories. This function is also carried out by other brain areas spread throughout the cortex and also included in the limbic system.
In more detail, we find the following functions of the hippocampus:
Consolidate learning
The hippocampus allows certain information that we integrate into our lives (or with which we relate) to pass into long-term memory (LTM). Thus, it acts as a “mediator” or facilitator between experience and memory.
Link memories with emotions
Furthermore, it links this type of content with certain values, whether positive or negative. What does this depend on? Whether memories are associated with pleasant (or pleasurable) or painful experiences, whether on a physiological or psychological level.
Store the memories
Once the experience is integrated into our long-term memory, one of the functions of the hippocampus, it is also in charge of another task: storing those memories in our biographical memory.
Manage declarative memory
We know that the hippocampus is related to memory, but especially with one of them: declarative memory. Declarative memory is a type of long-term memory, which refers to the memories that we can consciously evoke (for example: specific events).
On the other hand, non-declarative memory (related to the memorization of movement patterns and motor skills) is managed by the basal ganglia and the cerebellum.
Regulates space navigation
Another function of the hippocampus is the regulation of spatial navigation. This has to do with the way we perceive space, that is, with how we mentally locate and maintain a three-dimensional space, through which we move. This includes taking into account its volumes and its references to mentally “move” through it.
Coordinates visual perception with memories
But there is more; The hippocampus could also be related to the coordination of what we perceive, at a visual level, with our previous memories.
This is confirmed by a study carried out in 2011 by Gollo and his team, scientists from the Institute of Interdisciplinary Physics and Complex Systems (IFISC), which revealed that the hippocampus is responsible for coordinating visual perception with the memories we have of what we have seen. It is perceived.
The hippocampus as an orchestra conductor
As we have seen, in reality, it is not so much that the hippocampus allows the acquisition, consolidation and storage of memories directly, but rather that it acts as a mediator of memories.
It would be something like an orchestra conductor who directs the musicians; some play at a certain time, and others don’t. The musicians would be the memories, which are activated and deactivated depending on their director (the hippocampus).
In this sense, we know that the functioning of memory is not a simple process; This has to do with the activation and deactivation of networks of neurons that are distributed throughout different areas of the brain.
In this way, the hippocampus does not simply store memories, but rather acts as an activation node that would cause certain memories to be activated and distributed throughout the brain.
Lesions in the hippocampus
As with any brain area or structure, an injury to the hippocampus entails a series of psychological and functional consequences. In this case, an injury to said structure can lead to alterations such as:
- retrograde amnesia: It is characterized by the inability to remember events that occurred before the brain injury or damage.
- Anterograde amnesia: new events are not consolidated in long-term memory; That is, it implies a difficulty in learning new things.
- Dementia (for example: dementia due to Alzheimer’s disease).
The psychological and cognitive consequences of injury to the hippocampus will depend on the specific areas of the hippocampus affected, that is, the extent of the injury, and also on the characteristics of the patient (age, brain plasticity…), among other variables.
Bibliographic references:
- Belloch, A., Baños, R. and Perpiñá, C. (2008). Psychopathology of perception and imagination. In A. Belloch, B. Sandín and F. Ramos (Eds.) Manual of Psychopathology (2nd edition). Vol I. Madrid: McGraw Hill Interamericana.
- Gollo, LL, Mirasso, CR, Atienza, M., Crespo-Garcia, M. & Cantero, JL (2011). Theta Band Zero-Lag Long-Range Cortical Synchronization via Hippocampal Dynamical Relaying. PLoS ONE, 6(3): e17756. doi:10.1371/journal.pone.0017756.
- Kolb, B. & Wishaw, I. (2006). Human neuropsychology. Madrid: Panamericana Medical Editorial.
- Lubenov, EV & Siapas, AG (2009). Hippocampal theta oscillations are traveling waves. Nature 459:534.
- Young, P.A. & Young, P.H. (2004). Clinical and functional neuroanatomy. Barcelona: Masson