It is living something and, at the same time, having the feeling that it already happened before. The phenomenon has not yet been fully clarified, but it is known that it occurs due to a erroneous exchange of information in the brain. The expression déjà vu means «already seen» in French and emerged in the 18th century, created by parapsychologist Émile Boirac. He believed that déjà vu was a flashback of other reincarnations. The phenomenon was already studied in ancient Greece and, over time, it gained other explanations. To the parapsychologydéjà vu can be a way of premonition. Spiritualists, on the other hand, believe that it may be related to an experience of the spirit, capable of leaving the body during sleep. Scientists are still trying to discover the reasons, but they are sure: the origin has nothing paranormal and is 100% organic.
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I’ve seen this before…
Lack of synchrony in the brain creates the false impression of repetition
1. You don’t even realize it, but your nervous system is always comparing the new information it receives and the situations it predicts may happen. For example: when seeing two cars approaching at high speed, it is common to predict that they will crash. These two impulses arrive together at the hippocampus, the region of the brain where such a comparison is made.
2. Déjà vu occurs when there is a desynchronization between the two stimuli upon arrival at the hippocampus. If, due to some alteration in the activity between neurons, the prediction is anticipated, you have the feeling that what is happening at this moment is something you have already experienced, that is, it is part of your past.
3. Then, you already know: you start to see a complete scene (it can even include sounds or smells!) and you are absolutely sure that you have been there, lived and seen it all. He even feels capable of “predicting” the next details, as if he were a fortune teller. But it’s all an illusion as long as your brain doesn’t go back to normal, which can last for a few seconds.
Even Freud wanted to explain déjà vu: for him, the phenomenon had to do with past fantasies or unconscious desires
CONSULTANCY Gilberto Xavier, neuroscientist at the Institute of Bioscience at USP
SOURCE Book The Déjà Vu Experienceby Alan S. Brown