Deja Vu


The term “déjà vu” is originally French, and means "already seen". Those who have experienced the feeling describe it as an overwhelming sense of familiarity with something that should not be familiar at all. Say, for example, you are traveling to Luxor for the first time. You are touring around in Al Karnak Temple, and suddenly it seems as if you have been in that very spot before. Or maybe you are having dinner with a group of friends, discussing current political topics, and you have the feeling that you have already experienced this very thing; same friends, same dinner, same topics.

Doctors and scientists have discovered several reasonable explanations for “déjà vu”. Now, we are going to go through the most acceptable explanations for this phenomenon:

Scientists at the Massachusetts Institute of Technology, say they have discovered the part of the brain responsible for déjà vu; they say neurons in the memory centers of the brain known as the hippocampus make a mental map of new places and experiences, and store them away for later use. They believe that déjà vu occurs when two events or places are so similar that they overlap and thus result in a déjà vu.

The Optical Pathway Delay

If your eyes both beheld something, but for some reason the message took just a fraction longer to reach your brain from your left eye, there is a chance that your brain may process the same event twice, making you feel like you have already seen it, even if it was only a thousandth of a second earlier. This theory has been antiquated after Déjà Vu being reported in a blind person.

The Divided Brain Function

The frontal lobes of the brain are tied to the future, the temporal lobes with the past and the limbic system with the present. In this area of the brain are the hippocampus associated with short-term memory and the parahippocampal cortex associated with long term memory. Upon proper functioning, there is seamless integration between the past, present and future. However, when excessive communication between short-term and long-term memories occurs, the present may begin to feel like the past. This happens when perceptions of the present are incorrectly filtered through the memory system of the parahippocampal gyrus and its neocortical connections responsible for recognizing memories from the past.

The Hologram Theory

This theory proposes that the brain, in trying to combine the information from all the senses to create a complete picture of the current experience, brings forward similar or related details from past experiences such as the same smell, sight or sound by retrieving them from long-term memory. These sensory impressions from past memories overlap with the impressions from the new experience and give it the appearance of having come from the long-term memory.

Malfunctioning between the Long-term and Short-term Memory Circuits

Somehow, specific information shortcuts its way from short-term to long-term memory storage, bypassing the usual mechanisms used for storage transfer. The details concerning this shortcut are not yet well understood. When this new, recent piece of information is drawn upon, the person thinks that the piece is coming from long-term storage and so must have come from the distant past.

*Cover Image Credit: Medical News Today

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SCIplanet is a bilingual edutainment science magazine published by the Bibliotheca Alexandrina Planetarium Science Center and developed by the Cultural Outreach Publications Unit ...
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