Déjà Vu: A Blast from the Past?

Written By: Sophie Gabreldar

Have you ever thought “I swear I’ve been here before!” in a completely new environment? Well, I certainly have! This sensation is known as déjà vu, a French phrase that means “already seen.” 

What is Déjà Vu?

Déjà vu describes the strange feeling that you have experienced something before, even when you know you never have. They are unusual but cool experiences that can tell researchers a lot about how our minds, and particularly our memories, work. For example, let’s say you go skiing for the first time. You’ve never done anything like it before, but you have a sudden memory of going down that exact same mountain, under the same blue sky, with the exact same snow beneath you!

It’s often nothing to worry about. In fact, approximately two-thirds of the population experience may experience this phenomenon. While déjà vu is fairly common, especially among young adults, experts haven’t identified a single cause.

A Common Theory About Déjà Vu

Although the main cause of déjà vu is still unknown, experts have some clues from one group of people who report more déjà vu than most. This group of people have a condition known as temporal lobe epilepsy. Epilepsy causes brain cells to send out-of-control electrical signals that may affect the other cells around them, and sometimes all the cells in the brain.  These signals move through the cells and cause what is called a seizure; this can result in people with epilepsy briefly losing control of their thoughts or their movements. In people with temporal lobe epilepsy, the seizures start in their temporal lobe. This is a part of the brain that is just above the top of your ears, and is important for making and remembering memories.

Most importantly for déjà vu researchers, people with temporal lobe epilepsy often report having déjà vu just before they have a seizure. This means that déjà vu is most likely linked to the temporal lobe of the brain. In people who do not have epilepsy, déjà vu could be a mini seizure in the temporal lobe, but one that does not cause any other problems because it stops before it goes too far. This connects back to the idea that déjà vu might be caused by a strong feeling of familiarity. The familiarity is signalled by brain cells in the temporal lobe but is noticed and ignored by another part of the brain that checks whether all the signals coming to it make sense. The part of the brain that does this checking might be in the frontal lobe, a part of the brain just above your eyes.

Is Déjà Vu a Cause for Concern?

Although researchers haven’t pinpointed the exact cause of déjà vu, we do know that it is a completely normal thing to experience every now and then.  So, the next time you experience déjà vu, try to sit back and embrace the uneasiness that comes with it!