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What Is DéJà Vu?

Science & Tech  (tags: brain, functions, mysterious, medicine )

- 1768 days ago -
French for "already seen," déjà vu has been under investigation for years by scientists, who have yet to offer a complete explanation for the phenomenon, though it's reportedly experienced by more than 70 percent of people at some point.

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Kit B (276)
Monday July 22, 2013, 9:23 am
Photo Credit: Kenneth Man |

Most people have experienced it at one point or another: déjà vu, the haunting sense that you've experienced something before.

French for "already seen," déjà vu has been under investigation for years by scientists, who have yet to offer a complete explanation for the phenomenon, though it's reportedly experienced by more than 70 percent of people at some point.

Recent research, however, has yielded some clues into what causes déjà vu. It seems to occur equally among men and women and across races, according to a 2003 study from the Journal of Nervous and Mental Disease, but déjà vu happens more often in people ages 15 to 25.

That fact has led some experts to believe déjà vu may be linked to neurotransmitters like dopamine, which are found in higher levels in teenagers and young adults — a hypothesis that gained traction after the peculiar case of a healthy 39-year-old man came to light. The man — a doctor by profession — was fighting the flu by taking amantadine and phenylpropanolamine, two drugs known to increase dopamine activity in the brain. Within 24 hours of starting the drugs, he reported intense, recurrent episodes of déjà vu. This case study, published in 2001 in the Journal of Clinical Neuroscience, reported that once the doctor stopped taking the drugs, his déjà vu also disappeared. Déjà vu and epilepsy Another insight into the causes of déjà vu comes from studies of epilepsy. There is a strong and consistent link between déjà vu and the seizures that occur in people with medial temporal lobe epilepsy, a type of epilepsy that affects the brain's hippocampus. The hippocampus plays a key role in managing short- and long-term memories. People with medial temporal lobe epilepsy "consistently experience déjà vu at the onset of their seizures," according to a 2012 report in the medical journal Neuropsychologia. This phenomenon has led some experts to propose that déjà vu, like an epileptic seizure, may be the result of a neural misfiring, during which neurons in the brain transmit signals at random and cause healthy people to experience a false sense of remembered familiarity. Virtual reality triggers déjà vu Because déjà vu is such a fleeting event — most occurrences last no longer than a matter of seconds — it's proved frustratingly difficult to study. But cognitive psychologist Anne Cleary of Colorado State University in Fort Collins has found a way to induce déjà vu using virtual reality. Cleary and her colleagues created 128 3D virtual-reality scenes of a town they called "Deja-ville" using the game "The Sims 2." The images were paired, with a courtyard that had a potted tree in the center, for example, matched with a similar museum gallery with a statue in the center. When volunteers exploring Deja-ville entered the second room, they reported feelings of déjà vu, but they weren't able to connect that feeling to the time they spent exploring the first room. "People do have an increased sense of déjà vu when the scene has a similar layout, but they're failing to recall the source of that familiarity," Cleary told Smithsonian magazine. Déjà vu may be related to some other phenomena that are equally challenging for scientists to explain. Jamais vu, or "never seen," occurs when a person experiences something familiar — like their own living room — but feels that they've never been there before. And déjà entendu ("already heard") occurs when someone is certain they've heard something before, like a snippet of conversation or a musical phrase, but cannot recall the precise time or place.

By: Marc Lallanilla | Live Science |

Roger G (154)
Monday July 22, 2013, 1:05 pm
noted, thanks!

S S (0)
Monday July 22, 2013, 1:20 pm
Thank you.

Nikki J (15)
Monday July 22, 2013, 2:10 pm
Thank you.

I experiencing deja vu ... it's the same story over and over...Kate and Wills have had a BIG baby boy - 8ibs +.. Kate's probably sleeping!

That's 3 direct heirs to the British (and commonwealth's) throne alive at the same time - last time it happened Queen Victoria reigned. I'm sure our lovely Queen Elizabeth is trying to out do her ancestor in every way she can!:)

So proud to be British! :)

Nikki J (15)
Monday July 22, 2013, 2:13 pm
PS ... it's going well in with our sporting achievement too! (but ssshh don't remind the Aussies their very confused us POMs are winning so much!) :P

Laura R (15)
Monday July 22, 2013, 2:25 pm
very interesting

Emma S (239)
Monday July 22, 2013, 3:02 pm
Keep feeling I've read that article before... I'll - er - get my coat.

Thanks, Kit.

pam w (139)
Monday July 22, 2013, 3:51 pm
Our brains evolved with powerful connecting skills....we're engineered to make connections between what we see and what we HAVE seen. Small cues can make powerful connections backward in time.

Lois Jordan (63)
Monday July 22, 2013, 4:04 pm
Noted. Interesting article, thanks, Kit.
Gee, and all this time, I just thought I was psychic! Just kidding...but there are many mysteries in the brain still to unlock and I find that fascinating.

MmAway M (506)
Monday July 22, 2013, 4:47 pm
I have experienced it Kit! That is such a great article/site I had to subscribe! THANKS Again YOU ROCK!!!!! xx

Dot A (182)
Monday July 22, 2013, 4:50 pm
Interesting research,
You certainly share good things with Care2, Kit - Thanks!
[it's not a BackToTheFuture kind of thing,.... :( ]

Kit B (276)
Monday July 22, 2013, 4:52 pm

I think we have all experienced some level of Deja Vu at some point in our lives. Some times I think it's a memory confusion of something that did happen with something that is happening. We may never know exactly what it is or what causes the experience. It may just be one thing that makes us unique and human.

Kit B (276)
Monday July 22, 2013, 4:56 pm

I think you will find, Marilyn that it is a good magazine for a subscription. Thanks for the sense of humor, you folks are fun.

Yes, the Brits are elated today. They have a new prince and Americans wonder what's the big deal.

Rose B (141)
Monday July 22, 2013, 5:51 pm
Yes I have this now and again

Vallee R (280)
Monday July 22, 2013, 6:50 pm
past lives?

Suzanne L (99)
Monday July 22, 2013, 8:18 pm
The first deja-vu experience I had at 8.and I remember it quite clearly. I've had the odd one since. Someone explained it to me as "a brain fart". Not elegant but not unrealistic. Interesting phenomenon and article. Thanks Kit.

Freya H (357)
Monday July 22, 2013, 8:26 pm
Had this recently, when I visited the campus of the high school that my uncle and father attended. I'd never been there before - yet one or two things struck me as SO familiar, and for a moment I thought that I remembered something. Then I realized that I was recalling a place with a couple features in common. That may have caused the deja vu.

Sosso Lapro (1)
Monday July 22, 2013, 8:55 pm
The deja-vu phenomenon is known and explained for a looong time! It is caused by some thinks like fatigue and stress. It is a (very tiny) gap between the time you see (or feel, hear, whatever) something and the time when your brain interprets it. It really is that simple. Plus, your brain is able to add fairy and details, just to make something look real from some random facts. So if you feel like you have seen that before, and it must go back to your childhood or something.... NO. It is just your "smart" brain which is trying to rationalise the "funny" things you have seen (funny in the sense that it is true, it is facts, but it doesn't make sens, it doesn't fit into the reality yet).

Sheila D (194)
Monday July 22, 2013, 9:29 pm
Can't explain it, but have had one experience with it when I was a child. Strange feeling I have never forgotten.. Interesting article; enjoyed it. Thank you.

Amy Fisher (11)
Tuesday July 23, 2013, 4:31 am
Fascinating article.

I experienced deja vu just once that I can remember. This happened a couple of decades ago when I was in my thirties. I was helping my sister plan a birthday party for her husband, and we walked into a party store in a geographical area where I never went on my own , as I didn't live in the area. I had the fleeting sense that I'd been in that store before, but I knew I hadn't. It wasn't part of a chain, either. The logical explanation might have been that I had seen that specific type of layout before, the way they set up and sold their merchandise, rather than seeing the actual store.

Jonathan H (0)
Tuesday July 23, 2013, 4:33 am

Past Member (0)
Tuesday July 23, 2013, 9:24 am
some times it's spooky. thanks

Terrie Williams (798)
Tuesday July 23, 2013, 9:38 am
Been there, done that....several times. ;)
Thanks for the article, Kit.

Jaime Alves (52)
Tuesday July 23, 2013, 2:58 pm
Noted, thanks.!!

Constance F (418)
Tuesday July 23, 2013, 8:22 pm
can I go off topic ? lol ! I used to be a meditator but now I am just lazy. But once I had the experience of sitting down for my usual 30 minute meditation, and when I rose from meditation, it was 4 hours later. Yep, that's right ~ 4 hours later ! but it felt like 10 minutes whizzed by. I wasn't asleep. My brother told me that they did a study once, and in meditation, the part of the brain that registers time and space shuts down ~ simply put. And that's exactly what happened. Fascinating isn't it ! So much in the brain to be explored, and to think we know so little of it really. Then again ~ I like mystery too.

Kit B (276)
Tuesday July 23, 2013, 8:25 pm

That's true meditation, Constance and it's rarely achieved. I often think about getting back to that, I have no doubt that it would help with good sleep.

. (0)
Wednesday July 2, 2014, 4:02 pm
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