Origin of Deja Vu Pinpointed

A study of deja vu has revealed that the source comes from the hippocampus. In the brain, the hippocampus is located under the temporal lobe, and forms an essential part of the limbic system. The limbic system deals with emotion, incentives, and emotional association with memory. There, the hippocampus contributes to the system by playing a significant role in memory.

New studies suggest that a certain part of the hippocampus named the dentate gyrus is responsible for "episodic" memories in the human mind. These memories come from our life's experiences, and enable us to tell between the differences of similar places and situations apart.

Déjà vu is where one experiences the feeling that they have already previously witnessed or experienced a situation. Often times, it is called "experiencing the future."

According to LiveScience, MIT neuroscientist Susumu Tonegawa says this finding explains why as people grow older, they tend to experience déjà vu. According to Tonegawa, the dentate gyrus jots down a certain situation's pattern, and keeps it for the body's future reference. Think of it almost as a computer keeping track of its activities, as well as an Internet history where cookies and temporary Internet files are stored for faster reference for later. What the dentate gyrus takes note of are visual, auditory, olfactory, and such senses that are stored in the memory to be retrieved in the future.

Tonegawa and his team of researchers managed to block the dentate gyrus's ability to recall information for future reference. In an experiment, Tonegawa and his group bred mice with a faulty dentate gyrus. The results were astounding, as they found out that the dentate gyrus really is the center for the theory of déjà vu. The mice that did not have the fully-functional dentate gyrus could not tell the difference between two similar situations. This comes in light that mice are known to have the ability to distinguish between two alike, but different situations. This conjecture that déjà vu comes from the dentate gyrus has been validated, and is hypothesized that the same thing happens in humans.

Déjà vu is a memory problem that is prominent among an aging population, as well as people suffering from brain illnesses such as Alzheimer's. Having located the source of déjà vu, Tonegawa says that "It's not surprising when you consider the fact that there's a loss of cells or damage that has been done to the dentate gyrus."

Dave Mosher. "Origin of Deja Vu Pinpointed." Live Science. http://www.livescience.com/health/070607_deja_vu.html