You have probably encountered déjà vu. This state (translated from French means "already seen") is experienced by 60-80% of people. It can occur at any time and is almost always fleeting. You enter the room and suddenly feel that you have already been here, although you are here for the first time. Like the hero of a science fiction movie, you are like stepping into the future.
Deja vu is one of the phenomena that science still cannot explain.
“Because it’s not clear what triggers déjà vu, it’s difficult to study the phenomenon in the laboratory,” says Michelle Hooke, assistant professor of neuroscience and experimental therapy at the Texas Medical Science Center.
Brain failure?
“According to many studies, about two-thirds of people have experienced déjà vu at least once in their lives,” says Hook. "Understanding how memory works sheds some light on why some people have more déjà vu than others."
The cases of déja vu are possibly related to the process of accumulating memory in the brain. Long-term memories, events and facts accumulate in the temporal lobe. Parts of the temporal lobe are responsible for recognizing familiar events and phenomena.
The connection between the temporal lobe of the brain and déjà vu is not fully understood. But research among sufferers of temporal lobe epilepsy has revealed an interesting pattern. This disorder disrupts the activity of nerve cells in the brain, which causes spasms. Scientists speculate that déjà vu causes electrical dysfunction in the brain.
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Epileptic seizures occur due to dysfunctional activity of neurons (nerve cells) in the brain, disrupting the electrical impulses that excite the neurons. These impulses travel throughout the brain, causing epileptic seizures.
"Clinical studies have shown that in some patients with temporal lobe epilepsy, deja vu occurs before epileptic seizures, almost as a warning," notes Hook.
But why does deja vu occur in healthy people who do not suffer from epilepsy?
Some scientists believe that this is a "glitch" in the brain. The neurons responsible for recognition and familiar phenomena are mistakenly triggered. As a result, the brain mistakes the present for the past.
In addition, abnormal electrical impulses leading to epilepsy can occur in healthy people, such as hypnagotic twitching, an involuntary muscle spasm when a person falls asleep.
Shrinking the path of neurons
Cases of déjà vu in healthy people can occur due to an "error" in the passage of neurons. This happens because the brain is constantly trying to create a holistic perception of the surrounding world with limited initial data.
A small amount of sensory information, such as a familiar smell, is sufficient for the brain to recreate a detailed memory. It is possible that déja vu is related to a malfunction in the memory system: sensory information bypasses short-term memory and instead reaches long-term memory. This gives rise to the strange feeling that we are already familiar with the only picture or situation we have seen.
In the visual system, sensory information travels along multiple pathways to the upper cortical centers of the brain (areas responsible for memory, attention, perception, thought, language, and consciousness). All information reaches these centers at approximately the same time.
“According to some theories, when there is a difference in the processing of information along these paths, perception is impaired and the brain perceives it as two separate messages,” explains Hook. - The brain perceives the second version, due to the slow passage, as a separate perceptual experience. The result is an erroneous feeling of something familiar (deja vu)."
According to Hook, scientists have yet to study the phenomenon of déjà vu and the mechanisms behind it: “There is no simple answer to the question of which mechanisms cause déja vu. But further research in the future may provide answers to these questions."