Youâ€™re walking down the corridor in a building you needed your carâ€™s GPS to find in a city youâ€™ve never visited in your life and suddenly, it happens: you think to yourself, â€œIâ€™ve been here before.â€
DÃ©jÃ vu â€“ that wonderful sensation that everything around you is right where itâ€™s supposed to be and you know it is because you swear youâ€™ve been there before. Itâ€™s a phenomenon that has plagued man since he started thinking and yet it is as big a mystery as how did the stone heads get on Easter Island? Even comedian George Carlin has given us his own spin on the phenomenon, calling it â€œvuja deâ€: the feeling that somehow none of this has ever happened before. Now it seems that scientists have located the origin of that wacky, mixed up sensation.
According to MIT neuroscientist Susumu Tonegawa, located in the center of the brain is a wishbone-shaped tissue called the hippocampus where memories are recalled. Within that center is an area called the dentate gyrus, which is responsible for generating the episodic memories that allow us to differentiate between similar situations. Research on mice whose dentate gyrus have been underdeveloped have a hard time distinguishing between similar, but notable different situations. Tonegawa believes that when neurons in the dentate gyrus misfire, the subject experiences what we know as dÃ©jÃ vu.
Psychologists have struggled to research the causes of dÃ©jÃ vu because it is so fleeting, many times lasting little more than a minute or two. Attempts have been made to recreate dÃ©jÃ vu using hypnosis, but the most desirable conditions would be to have someone experience dÃ©jÃ vu while receiving a brain scan mapping activity.
In some cases, however, dÃ©jÃ vu isnâ€™t a once in a while occurrence. Chris Moulin director of the memory clinic University of Leeds in the UK has been studying a condition where dÃ©jÃ vu is chronic â€“ even to the point that one patient referred to him balked at visiting Moulinâ€™s clinic because the patient was certain he had already been there when there existed irrefutable proof that he had not. When once asked by his wife what would happen next on a TV show he claimed he had seen before he responded, â€œHow should I know, I have a memory problem?â€
Since Moulinâ€™s initial encounter with the man suffering chronic dÃ©jÃ vu, he and his staff have located many more patients with the same condition and know what to look for. The condition can cause depression and has been diagnosed as a state of delusion. Moulin and his associates offer an alternative theory â€“ that it is dysfunction of memory. In some cases of brain damage and in Alzheimerâ€™s patients, dÃ©jÃ vu can also become chronic. Once it was thought dÃ©jÃ vu was the result of visual images from one eye arriving in the optic center of the brain a microsecond before the image from the other eye. This theory was seriously damaged when a blind man reported that he has experienced dÃ©jÃ vu based only on the sounds, smells and activities around him at the moment.
With its mysterious attributes as plentiful as the concept of an afterlife, dÃ©jÃ vu continues to puzzle psychologists and elude extensive study. Unlocking its mystery gives psychologists something constructive to do and you something to think about when youâ€™re walking down the corridor in a building you needed your carâ€™s GPS to find in a city youâ€™ve never visited in your lifeâ€¦
Information synthesized from multiple articles on LiveScience.com.
Copyright © 2010 D. E. Carson
Been There, Done That - or Not
Copyright © 2010 D. E. Carson
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