The hippocampus is a part of the limbic system of the brain that controls learning and memory, abstract and analytical thinking. Like most nervous structures, the hippocampus has a paired structure. One part in each hemisphere, in the temporal lobe. Between them they are connected by nerve fibers. When scientists discovered this part of the brain, they thought its shape was very similar to a seahorse. Literally from the Greek, the hippocampus translates as curved horse.
Why do we need him?
The hippocampus is needed for a lot of important things:
1. First, it manages memory.
All of our knowledge and skills, memories and significant life events are its job. The hippocampus sorts all incoming information: necessary/unnecessary, important/unimportant, valuable/useless. It selects everything to be memorized and transfers it from short-term memory to long-term memory. All these processes occur mostly in sleep.
The hippocampus is also responsible for remembering faces, an ancient type of memory that allowed our ancestors to quickly distinguish enemy from friend. And it's also responsible for remembering emotions. Therefore, we may not remember all the details of the event, but we clearly retain the feelings experienced at that moment.
2. The hippocampus is responsible for orientation in space.
This is our navigator, which memorizes the terrain, saves it as a "map" and builds the same route the next time. It also searches for the shortest route. There is a famous study of London cab drivers, which showed a direct correlation between the length of service and the volume of the hippocampus. The longer a person worked as a cab driver and studied the city, the bigger his hippocampus became.
3. Neurogenesis.
It's about "nerve cells don't regenerate". For a long time it was believed that the bulk of neurons are formed in childhood, and in an adult they can only die off due to age-related changes and stress.
But no!
As we age, only the rate at which nerve cells and networks are created decreases. But the process itself does not stop.
Neurons are "born" when a person thinks, solves problems, engages in creativity, and has new experiences.
The main neuron factory is the hippocampus. It produces about 700 new neurons every day.
4. Regulation of emotions.
The hippocampus is a companion to the amygdala, which we already know. Anatomically, the amygdala is directly attached to the hippocampus. In a situation of uncertainty, all parts of the brain "ask" the hippocampus, "Is this dangerous or not? Is it going to be okay? Will we survive? " The hippocampus quickly navigates through everything that the amygdala has previously recorded, and if something seems dangerous to it, it immediately "turns on" the amygdala as a signaling system. And she further sends rescue signals to the entire body.
If the amygdala is activated, e.g. by a threat, the hippocampus is instructed to remember what we are experiencing. In this way, it creates a corresponding memory - clear and with good resolution. Even years later, we can remember events in such detail as if they happened yesterday. Such memories are easily awakened: even individual impressions remind us of what happened.
In other words, when the brain creates distinct and easily awakened memories of traumatic events, there is nothing wrong with it. Its primary job is to make sure we survive even in the worst case scenario. The brain makes sure we avoid dangerous situations in the future.
Hippocampal function can be impaired due to:
- Trauma (for example, the consequence of trauma can lead to the development of amnesia - loss of memory of previous events);
- Neurodegenerative processes against the background of alcohol or drug use;
- Epilepsy - 75% of patients have pathologies and defects in the function of the hippocampus;
- Alzheimer's disease - this is why memory and orientation in space deteriorates, and in severe forms a person ceases to recognize their loved ones;
- Korsakov syndrome with similar symptoms;
- Long-term stress and excessive levels of cortisol (stress hormone) - this also hits the hippocampus and leads to mass death of neurons. They are destroyed faster than new ones are created.
The result is cognitive impairment in the form of poor memory, absent-mindedness, thoughts of "where was I going and why?". This also happens in depression.