A blog on biology, psychology, cognition, learning, memory, aging, and everything in between. Explaining recent discoveries in neuroscience, translated to language we can all understand!
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Déja vu is a French term that literally means "already seen" and is reported to occur in 60-70% of people, most commonly between the ages of 15 and 25. The fact that déja vu occurs so randomly and rapidly—and in individuals without a medical condition—makes it difficult to study, and why and how the phenomenon occurs is up to much speculation. Psychoanalysts may attribute it to wishful thinking; some psychiatrists cite mismatching in the brain causing us to mistake the present for the past. Still, parapsychologists may even believe it is related to a past-life experience. So what do we know for certain about what happens during an episode of déja vu?
Some researchers speculate that déja vu occurs when there is a mismatch in the brain during its constant attempt to create whole perceptions of our world with very limited input. Think about your memory: it only takes small bits of sensory information (a familiar smell, for instance) to bring forth a very detailed recollection. Déja vu is suggested to be some sort of "mix-up" between sensory input and memory-recalling output. This vague theory, however, does not explain why the episode we experience is not necessarily from a true past event.
|Ventral (bottom) view of the brain, showing the perirhinal (red) and entorhinal (yellow) cortices.|
Bartolomei F, Barbeau EJ, Nguyen T, McGonigal A, Régis J, Chauvel P, & Wendling F (2012). Rhinal-hippocampal interactions during déja vu. Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology, 123 (3), 489-95 PMID: 21924679
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Or we are living in the Matrix...nah!
Very nice blog post (and I like the shoutout to french people!)
Deja Vu is also a nice way to explain to non-medical/scientist people about several theories of conciousness (different modules aggregating into one narrative, etc), because it is a phenomenon that most people have felt.
Very interesting article!
I'm just a little curious if you could elaborate more on what you mean by "One characteristic is common of all déja vu experiences: we are completely conscious that they are occurring, implying that participation of the entire brain is not necessary to produce the phenomenon."
And might this be a start on a series of dissociation disorders? That would be fun :)
Oops! I meant a series on* dissociation disorders. I hope you won't be falling prey to any dissociation disorders haha.
Thanks for the comments!
Cynthia, you know how during a deja vu episode, almost from the moment it starts, you're thinking in your head, "I'm having deja vu, I'm having deja vu" over and over until the feeling passes? You're completely aware it's happening. Compare that to having a dream: the weirdest things can be going on, but you don't realize it until you wake up and think, "Huh, a tapdancing narwhal..." Deja vu must leave some of our higher consciousness and awareness processing alone in the cortex, so the fact that it may be happening in somewhere like medial temporal lobe could make sense.