Almost all of us have experienced what is called deja vu : a strange feeling to say that the new events we are feeling we 've actually experienced much earlier . This event could be a new place being visited , conversations are being conducted , or a TV show that is being watched . More strangely again , we are also often not able to really remember when and how it occurred prior experience in detail . All we know is the mysterious sensation that makes us not feel strange about the new event .Strangeness of the phenomenon of deja vu in turn gave some metaphysical theories that try to explain causality. One is the theory that deja vu is actually derived from a similar incident ever experienced by our souls in one previous reincarnation of life in the past . How to explain the science of psychology itself ?Associated with Age and Degenerative DiseasesAt first , some scientists believe that deja vu occurs when optical sensations received by the eye to the brain ( and perceived ) first rather than the same sensations received by the other eye , causing a feeling familiar to something that is actually the first time seen . Theory known as " optical pathway delay " was broken when in December last year found that people can experience deja vu butapun through the sense of smell , hearing , and perabaannya .In addition , previously Chris Moulin of the University of Leeds , UK , have found also sufferers of chronic déjà vu : the people who are able to explain in detail the events that never happened . They felt no need to watch TV because they feel have been watching the TV show before ( but not yet ) , and they did not bother to go to the doctor to treat ' penyakit'nya because they felt it was going to a doctor and can tell the details during his visit ! Instead of misperceptions or delusions , researchers began to look into causes of deja vu in the brain and our memory .More recently , an experiment in mice may provide new insight about the origin of the actual deja vu . Susumu Tonegawa , an MIT neuroscientist , bred mice lacking a number of the dentate gyrus , a small part of the hippocampus , which is functioning normally . This section previously known to be associated with episodic memory , the memory of our personal experience . When encounter a situation , the dentate gyrus will note signs of visual , audio , smell , time , and other signs of the senses to be matched with our episodic memory . If no match is found , this situation would be ' registered ' as a new experience and recorded for future comparisons .According to Tonegawa , normal mice have the same ability as humans to match the similarities and differences between some situations . However , as expected, the mice that the dentate gyrus is not its normal function and then have difficulty in distinguishing the two situations are similar but not identical . This, he added , could explain why the experience of deja vu increases with age or the emergence of degenerative diseases such as Alzheimer's disease : loss or damage to the cells in the dentate gyrus due to two things make it hard to determine if something is ' new ' or ' old ' .Creating ' Deja Vu ' in the LaboratoryOne of the things that made it difficult for researchers to unravel the mystery of deja vu is spontaneous and natural occurrences can not be predicted . A researcher can not simply ask participants to come and ' told ' they are experiencing deja vu in a sterile lab conditions . Deja vu generally occur in daily life , where it is not possible for the researcher to constantly connect participants with brain scanners are bulky and heavy . In addition, the rarity of deja vu going to make follow participants anywhere at any time is not a thing to be done efficiently and effectively . However, some researchers have managed to simulate conditions similar to deja vu .As reported by LiveScience , Kenneth Peller from Northwestern University found a simple way to make someone have a ' false memories ' . The participants were shown a picture , but they were asked to imagine a totally different picture in their minds . Having done several times , the participants were then asked to choose whether a particular image they actually see or just imagined . It turns out the pictures were only imagined participants often claimed they actually saw . Therefore , deja vu may occur when by chance a person experienced similar events or similar to the picture I ever imagined .LiveScience also reported experiments Akira O'Connor and Chris Moulin of the University of Leeds in creating the sensation of deja vu through hypnosis . The participants were first asked to recall a series of lists of words . Then they hypnotized so that they ' forget' those words . When the participants were shown a list of similar words , half of them reported a similar sensation like dejavu , while the other half are confident that they are experiencing is really deja vu . They think this happens because the brain areas associated with familiarity harassed her by hypnosis .