Déjà Vu and Science's Point of View
by Emjay Rosales
Isn’t it strange to feel like you have been in this present situation before?
You might think it was just another version of you trying to give a glimpse of the parallel universe, or recollecting some significant memory of your past life. But these parapsychology conjectures and other devious speculations about this phenomenon have long been debunked by scientists. This strange feeling of familiarity that an individual has already encountered a situation before is called déjà vu, and it is a neurological phenomenon, not a supernatural manifestation.
WHAT IS DÉJÀ VU?
Déjà vu is a French word which literally means “already seen,” defined as “any subjectively inappropriate impression of familiarity of a present experience with an undefined past,” said internationally-known neuropsychiatrist Vernon Neppe, M.D., Ph.D. In a simplified language, it is when there is a feeling that a present situation has happened somewhere and somehow in the past.
About two-thirds of the population experiences déjà vu, and frequently happen to young adults between ages 15 to 25. Kids six years old and above are also believed to have experienced this phenomenon.
Despite its rarity and random occurrence to people, there have been powerful insights and theories that could be the foundation of déjà vu’s medical explanation.
WHY DOES IT HAPPEN?
In the March 2012 issue of Clinical Neurophysiology journal of National Center for Biotechnology Information, a study claimed that déjà vu is caused by “acute disturbance of mnemonic systems of medial temporal lobe.”
The medial temporal lobe (MTL) includes a system of anatomically related structures that are essential for declarative memory (Squire, et al. 2004). In the process where the subjects of the study were epileptic patients with electrical stimulation-induced déjà vu experiences, they analyzed intracerebral electroencephalography (EEG) signals through the other components of these patients’ MTL—the rhinal cortex, the hippocampus which is responsible for the memory function, and the amygdala which is responsible for emotion.
In result, the increased EEG signal corresponding to MTL structure is linked with déjà vu. The study concluded that the somewhat strange familiarity may “trigger” the activation of the recollection system (Bartolomei, et al. 2012).
DELAY OF INFORMATION
Another study explains that there is a dysfunction of neural transmission speed or simply the pathway delay when it comes to experiencing déjà vu. In this case, there could be a brief change of transmission speed, either speeding up or slowing down, in a single neural pathway where new data is being misrecognized as old.
The dysfunction can also occur in dual pathways where the perceived stimuli—two information, for example—travels through several pathways on its way to cortical centers where they would meet and merge as one unique information, arriving with a slight time difference. But when the transfer from one pathway gets delayed, the two information being perceived as “one” would be interrupted (Comfort, 1977). Thus, there is a reason why there is a strange feeling of familiarity because of the brief delay of the arrival of sensory information in the cortical areas.
A GLIMPSE OF THE FUTURE?
There are also instances when an individual somewhat predicts what is about to happen next when experiencing déjà vu. The explanation is, when the primary pathway—wherein the human’s initial perception travels through—arrives after the secondary pathway—wherein the “past experience information” lies through—the feeling of being clairvoyant would arise.
Some studies also conclude that déjà vu happens when past and present experiences overlap with each other. The present situation’s perceptions are re-routed from the short-term circuit of the brain to the long-term storage where the brain processes past memories.
Amygdala also explains the phenomenon. This tiny region of the brain which is also responsible for fear factors can produce stimulus that can release panic response. When you are put in an altered familiar situation—for example being in a situation that seemed to happen before but is different somehow—amygdala could leave you temporarily confused, thus déjà vu.
WHO ARE PRONE TO DÉJÀ VU?
People who travel have high reports of déjà vu frequency. This is due to the novelty or the “newness” they get from new locations and experiences through travelling, because this alone is available for déjà vu probabilities.
People with higher education are more prone to this phenomenon as well. One reason is because of the higher novelty from the acquired new sources. Another factor is the higher chance of being employed which has trigger options for déjà vu, e.g stress.
In a nutshell, déjà vu is perceived as just a reaction produced by the failure of our brain to comply with their respective tasks. This second-lasting experience is quite fascinating, especially for people having a lot of imaginary thoughts that sometimes lead to pseudo scientific prejudice. This is the reason why researches are important so people do not have to cling to baseless judgments without digging into the causality of a phenomenon first. Déjà vu is just one example that science truly gives explanations to things that are seemed mythical.