Long story short, it all relates to memory. Apparently, when we experience deja-vu, the decision-making area of our brain is being activated.
Basically, during a deja-vu, our brain is confronting its memories, just to make sure that they really are accurate – because it knows you’ve never experienced a certain thing before.
The theory is supported particularly by the fact that nearly all the people who experience deja-vu are young, which means that their brains are healthy and more active – just like their memory. However, we can’t deny that this sensation is truly mindblowing – and it will still remain one of the greatest mysteries of the human brain.
