Minggu, 15 Juni 2008

DE JAVU



Deja-Vu; the feeling that you are re-experiencing some specific event from the past in the present. Dejavu happens to everyone at one time or another. But do you ever stop to wonder what it really is? Have you assumed that it was some sort of paranormal psychic event? A past life regression? Perhaps you assumed that it was exactly what it feels like, remembrance of a past event. Perhaps you thought it was indigestion. Lay off the meatballs dude! Studies have shown that dejavu is primarily visually oriented. You see something, and suddenly get that dejavu feeling. The visually triggered Dejavu is by far the most common occurrence, but I know that I've encountered audible and scent based Dejavu in the past. So what is dejavu?
First of all lets get a definition out of the way, so we're all on the same page. I had a difficult time finding one adequate definition, so the definition below is a compilation from various dictionary references.
Dejavu (day zha voo), [Fr., lit., already seen]: In psychology, the illusion that one has previously had a given experience. The feeling that you are re-experiencing some specific event, sound, or scent from the past in the present. An impression of having seen or experienced something before.

Now that the definition is out there, let's get on with some scientific background. I once read, and have no idea where I originally read it; about the scientific causes of Dejavu. I was able to find a web reference that basically covers what I read in the past. The scientific explanation for dejavu goes something like this... It's caused by a chemical imbalance in the brain. When events are occurring in the present, our brain processes the activity in a part of the brain called the amygdala. Dejavu occurs when present events are processed in a part of the brain typically used to recall past memories. The parahippocampal cortex, which is very closely connected to the hippocampus. Because the event is processed in the parahippocampal cortex, it has a past 'flavor' associated with it.
There you go. That's the gist of the scientific explanation for this phenomena. I've also read supporting materials that state that dejavu can also be triggered by transmission delays in the optic nerve. That delays between the image received by one of the eyes, can cause the brain to experience dejavu. This may be true, but does not fully explain audibly (or scent) triggered dejavu. The root cause of dejavu appears to be a chemical imbalance in the brain. The imbalance may be caused by a variety of reasons (including the optic one mentioned above). The imbalance causes memories to be processed by an inappropriate part of the brain. Processing of the data by the parahippocampal cortex gives the information a 'past flavor'. If the data had been processed correctly, by the amygdala, then it would have had the correct 'present flavor'.
Now that we've gotten the scientific part as a foundation, let's explore a little conspiracy theory. The original article that I read went into an in depth description of how these scientists had done experiments on mice (and other animals) in an attempt to prove that this chemical imbalance was the true cause of dejavu. They eventually concluded that it was in fact caused by a chemical imbalance. In their human studies, they were able to locate individuals who experienced dejavu quite often, some individuals reported experiencing dejavu hundreds of times a day. Brain scans showed these individuals to have damaged amygdala's.

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