Science
Déjà vu
Re-living the Present
Have you ever been in a situation where you are walking down a street, and suddenly you go, “I think I’ve walked here before”? Or when a pencil rolls down a table, you feel like you have seen the exact scenario before? That is what déjà vu feels like.
Déjà vu is a French phrase which translates to “already seen”. It is the transitory sensation of having experienced a similar situation, which has never happened. It is the feeling of familiarity with the incident that is just happening. For example, you might be having a conversation with your friend when suddenly, you being in the exact moment before, flashes in your memory, except that the same moment has never happened.
Research and surveys say that younger people experience déjà vu the most. Usually, memory problems increase with age, but déjà vu decreases with age, indicating that déjà vu is not a memory problem.
What Causes Déjà vu
Well, the answer to this fundamental question is still a mystery. Researchers have tried to figure this out with the help of a group of people who get déjà vu the most- people with a condition called “temporal lobe epilepsy” have been reported to experience déjà vu at a higher frequency. These people get seizures when the brain cells send out-of-control electrical signals that affect the other brain cells like dominoes, causing a loss of control of themselves temporarily. These seizures start in the temporal lobe, which is responsible for memories. Déjà vu occurs just before seizures in these people which implies that déjà vu has something to do with the temporal lobe.
But the next question arises. What causes déjà vu in people without epilepsy? One possible explanation for this is that déjà vu could be a mini seizure, the kind that stops before it goes too far and cannot be sensed. The theory is that the brain cells in the temporal lobe signal familiarity, but the frontal lobe, the decision maker, notices it but ignores the message, as it wouldn’t make any sense.
Glitch in the Nervous System
This theory explains that déjà vu is caused due to a delay in the neurons’ transmission speed. To understand this accurately, imagine a crow flying with a magic wand. You’ve more than likely never seen a crow flying with a magic wand, but if you are experiencing déjà vu, the probable reason is that the information passing through your eyes and to your brain is reaching at different times. Maybe the information from the left eye reaches the visual cortex just before the information from the right eye reaches there. These happen in a very short period, such that the left eye’s information is not stored as memory yet. But since the brain receives the information twice, we sense familiarity.
Beyond these explanations, a number of theories attempt to explain why we might experience déjà vu. Some say it’s like a short in the circuits in our brain leading to a conflict between long-term and short-term memory. The new incoming information goes straight to long-term memory instead of making a stop in the short-term memory bank. Others blame the rhinal cortex — the part of the brain that causes the feeling of familiarity — for somehow being triggered without the memories to back it up.
Mystical Theories
This explanation makes us wonder what if we have actually lived the moment before but in a different life. This comes from a common theory which states that when we die, we see a huge bright light- the light at the end of the tunnel. It is believed that the light is us being born again. Some of the memories from the past life aren’t fully wiped out. These memories cause déjà vu when that moment happens in the new life.
Other theories state that déjà vu is caused due to overlap or sync in our parallel universes. According to the parallel universe theory, an infinite number of universes exist alongside our current universe. In these parallel universes, the same person could be doing an infinite number of different activities. The best way to understand this is to consider the working of a radio. There are numerous frequencies, but we can listen to only one frequency at a time because they operate at different wavelengths and levels.
Similarly, according to parallel universe theory, different universes vibrate with different frequencies, but we cannot notice their existence. The theory states that sometimes, two universes come in phase with each other, and interact for a short period. The belief is that when your actions correspond exactly, just after another you in a parallel universe, you feel as if you had already experienced it. This is because in the other universe you had done the same action.
Most of the theories land at a common point — déjà vu is caused due to asynchronous connections between the parts of the brain that are responsible for memory recollection and familiarity.
When Should we be Worried?
Déjà vu can sometimes make us feel uncomfortable, depending on what you think you have already experienced. To overcome this, one can adopt simple methods-
· Distracting ourselves with our favourite activities
· Counting numbers, say till 10 or 20, depending on when the feeling goes away
· Rubbing fingers and focusing on the temperature and fingerprint patterns
· Mindful breathing
It is found that people who are stressed out and are under pressure tend to experience déjà vu often; this is because stress is linked to memory which is the central aspect of déjà vu. So, if you frequently experience déjà vu, you need to get more sleep and take initiative to reduce stress. If that doesn’t work too, it can be a sign of epilepsy, for which consulting a neurologist is advised.
On a positive note, Deja vu can also indicate good memory because it’s common in younger people and is believed to be a healthy reaction. So, one does not have to worry about getting rid of the feeling! It is all about being able to know if we can handle it, or if a medical consultation is required.
