Déjà Vu and Disorders

Many scientist believe that deja vu is a result of a chemical reaction in the brain, either triggered by sensory input and recalling a memory, like smelling rose perfume and remembering a funeral, or by minor seizures in the temporal lobe of the brain.

Though there is still no indication directly of the cause of deja vu, scientists have been able to document an association between epilepsy that effects the temporal lobe and deja vu. Often, patients with this from of epilepsy will report that they experienced a strong sense of deja vu immediately before the onset of an epileptic attack. Other patients have reported that experienced deja vu while in the midst of seizure activity.

However, 70 percent of people claim to have had a deja vu experience at some point and scientists are not willing to diagnose them all with some form of epilepsy or other brain disorder. However, some will acknowledge that as much as 65 percent of the population has occasional non-pathological epileptic seizures, like the full body muscle jerk as one is falling asleep.

Scientists have also been able to associate deja vu experiences with anxiety and schizophrenia, but argue that the mostly likely cause of deja vu is a mix-up with memory.This theory is based in the idea that people experiencing deja vu can often not provide details of when they experienced this event, feeling or place before. It is also argued that sometimes the feeling of deja vu itself cannot be explained later. The person who had the feeling may not even been able to explain what it was that they had already seen or done. Scientists argue that this is evidence that the brain is playing tricks on itself.

It has also been argued that deja vu may be a side effect of mind-altering drugs distorting a person’s sense of reality and time. Scientists have been able to replicate deja vu in the laboratory using recreational drugs and pharmaceuticals designed to treat other conditions, like the common cold.

One final theory, though incredibly hard to quantify, is the concept that deja vu is caused by the brain reacting to two different stimuli inputs a fraction of a second apart from one another. In this theory, the concept is raised that perhaps if the optic nerves misfired. One eye provides the brain with an image and the same image is transmitted to the brain with a miniscule delay from the other eye, confusing the brain into thinking that it has experienced this event previously.

This theory though scientifically sound cannot be tested because we do not have the technology to measure brain reactions in the tiny amount of time involved. Any experiment trying to delve into this theory would be hampered by the amount of time it would take researchers to provide duplicate images to the brain and by the subject’s awareness that the delay is occurring.