Interestingly, a chronic neurological condition gave the researchers some clues.
Most of us have experienced the weird phenomenon known as known as déjà vu — essentially, experiencing something that fills you with the odd sensation that you’ve experienced that very moment sometime in the past.
In fact, déjà vu occurs in approximately 60 to 80 percent of people, so the strange feeling is not uncommon, but these momentary sensations are still misunderstood by the scientific community despite their commonality, according to a new press release on the topic.
Researchers in the Department of Neuroscience and Experimental Therapeutics at the Texas A&M Health Science Center College of Medicine have published new research on déjà vu, providing deeper insight into the mysterious phenomenon.
"Because there is no clear, identifiable stimulus that elicits a déjà vu experience (it is a retrospective report from an individual), it is very difficult to study déjà vu in a laboratory," said Michelle Hook, an assistant professor in the Department of Neuroscience and Experimental Therapeutics.
"According to many studies, approximately two-thirds of individuals have experienced at least one episode of déjà vu in their life," Hook said. "Understanding how memory storage works may shed some light on why some experience it more than others.”
Interestingly, understanding a chronic neurological condition called temporal lobe epilepsy may hold an explanation for why we experience déjà vu — and it all boils down to electrical impulses in the brain.
The temporal lobe is where we make and store long-term memories, and specific parts of the brain region are also critical for detecting familiarities or recognizing certain events. Episodes of déjà vu are likely related to how our memories are stored in the brain, but the phenomenon’s link to the temporal lobe and memory retention still has yet to be confirmed.
However, the new study at Texas A&M suggests that déjà vu events may actually be caused by an electrical malfunction in the brain — an integral characteristic of temporal lobe epilepsy.
"Clinical reports show that some patients who suffer from temporal lobe epilepsy report experiencing déjà vu, almost as a sort of warning, before an epileptic seizure event," Hook said.
But what is the basis for déjà vu in people without temporal lobe epilepsy? The researchers describe it as a “glitch in the brain” — when the neurons for recognition and familiarity fire, they end up causing the brain to mistake the present for the past.
In fact, the same abnormal electrical impulses that contribute to epilepsy can present in healthy people,” the press release states.
Further, the researchers say that déjà vu in healthy people could suggest a “mismatch” in the brain’s neural pathways. Our brains are constantly trying to generate a whole, meaningful perception of the world around us, but there’s limited input information, so our star organ is bound to mess up at times.
For example, all it takes is a familiar smell for the brain to suddenly create a detailed recollection of something. Therefore, déjà vu could be the result of sensory information bypassing the short-term memory and reaching the long-term memory instead, creating that unsettling feeling that we’ve already experienced a new moment.
When it comes to our brain’s visual system, sensory information travels through a number of pathways in the higher cortical centers in the brain — the areas that play a key role in memory, perception, awareness, thought, and consciousness — and all information reaches those centers at around the same time.
"Some suggest that when a difference in processing occurs along these pathways, the perception is disrupted and is experienced as two separate messages,” Hook explains. “The brain interprets the second version, through the slowed secondary pathway -- as a separate perceptual experience -- and thus the inappropriate feeling of familiarity (déjà vu) occurs.”
Hook admits that there’s still a lot to learn about déjà vu and the brain mechanisms behind the strange phenomenon.
"There may not be a simple answer for the mechanisms behind déjà vu yet, but, with further research and studies, conclusive evidence for the phenomenon may be discovered in the future.”
Nevertheless, it’s still intriguing to follow along as scientists slowly but surely put the puzzle pieces together.