Have We Been Here Before?: Déjà Vu and its Implications on the Brain
Most people have experienced déjà vu, which was translated as “already seen” by Émile Boirac, a French psychic researcher, in the late 19th century (2), at least once in their lives; when partaking in one of the day’s numerous menial activities, we have had an eerie stirring from within us, coupled with the strange feeling that we have done the exact thing before. It is not a feeling of familiarity, but instead a feeling of duplication, a carbon copy of what one has dreamt or seen before. Déjà vu, also called paramnesia, affects upwards of 70 percent of the population, with varying degrees and frequency, and occurs most often in the 15 to 25 age range (1). Being one of these people, I am extremely interested in the implications of déjà vu, as well as in what it can suggest about the functioning of my brain.
Arthur Funkhouser believed that there are three main types of déjà vu. Déjà vecu, meaning “already experienced or lived through,” occurs most frequently, and is what most people are referring to when they discuss déjà vu. This occurs most often in the 15 to 25 age range, because the still-developing brain is sensitive to minute changes in the environment. This could also be why such simple things can set the brain off, oftentimes with the person being able to predict what will happen in the next few moments. Of déjà vecu, Charles Dickens wrote, “We have all some experience of a feeling, that comes over us occasionally, of what we are saying and doing having been said and done before, in a remote time – of our having been surrounded, dim ages ago, by the same faces, objects, and circumstances – of our knowing perfectly what will be said next, as if we suddenly remember it” (2)! Déjà senti, meaning “already felt,” is mostly experienced in the mind, unlike déjà vecu, which is experienced with the whole body. While déjà vecu remains in a person’s memory, a person who experiences déjà senti will rarely ever remember it. It comes out of nowhere and is gone in a short time, leaving no residual feelings, not even a recollection of what happened. Consequently, it can be experienced by those suffering from temporal-lobe epilepsy. Déjà visité, translated as “already visited,” the least common of the three, is when a person, without having real, physical knowledge of a place, knows its intricate details that only a person who had been there before would know. The main the difference between déjà visité and déjà vecu is that while déjà vecu deals with personal feelings, déjà visité only deals with geographical knowledge. A person may not have any feelings of having been somewhere before, but he may have a highly detailed knowledge of the place (2).
Oftentimes, déjà vu is related to temporal-lobe epilepsy, with sufferers claiming that it occurs right before, during, or between convulsions (1); however, this does not necessarily imply that déjà vu is directly linked to epilepsy, because, most people experience a mild epileptic episode at least once in during a lifetime, such as the hypnagogic jerk that is experienced before one falls into a deep sleep. Due to this fact, it is possible that similar mild epileptic neurochemicals cause the false sense of a repeated memory to be created. Déjà vu is also prevalent in those who suffer from afflictions like anxiety and schizophrenia, and occurrences can be increased through the use of certain medications; in 2001, a healthy man had a high rate of déjà vu after taking the cold medicines amantadine and phenylpropanolamine together. Psychologists Taiminen and Jääskeläinen deduced that it is probably caused by “hyperdopaminergic action in the mesial temporal areas of the brain” (2).
Skeptics of déjà vu have used various reasons in the attempt to demystify all three types of occurrences. Many say that déjà visité is often the result of hearing or reading an in-depth description of a place. For example, in his book Our Old Home, Nathaniel Hawthorne knows the layout of a castle that he is visiting for the first time; however, he finally realizes that he knows the place because he had read the description of the ruins that Alexander Pope had written two hundred years before (2). Another argument, aimed at déjà vecu, is that it is simply a mental reaction that one has as a result of a memory fragment; if a memory is not properly stored, due to age or distraction, only pieces of the experience are recorded. If a situation in the present is similar to a fragment from the past, the mind is unable to place the previous memory and, in its confusion, thinks that the situation is brand new, in an eerie sort of way. A scent, a setting, or a stock phrase can set it off, but the mind just does not recognize the previous experience. Skeptics also believe that the public should not be talking about the déjà vu experience, but simply the “déjà vu feeling;” it is not the familiarity of the situation that disarms us, but instead the feeling of strangeness that accompanies it (3). Another explanation is that because one eye records objects slightly faster than the other can, creating a sense of having seen something before; this would make the scene tied to a previous memory, but the memory is only fractions of a second old (2). Others believe that it is possible that neurochemical action in the brain that is not connected to any previous memories, causing one to associate a feeling with an intangible memory that has never really occurred (3). It is as if one of the boxes in the brain that does not accept an input signal randomly creates an output, which is the strange feeling, the feeling of false familiarity.
Déjà vu has been discussed in various literary works in the last few centuries, implying that it is not a disorder that has had a strong onset in the last decades or so (2). Unlike Alzheimer’s disease, which has seen a drastic spike in the last thirty or so years, or small pox, which is almost eradicated in present day, déjà vu has fairly maintained its statistics; also, I have found no research to indicate that there has been anything more than a slight change between having it for no reason or having it be a marker of a more serious condition. In addition, it can occur in those with or without a mental condition, which makes it increasingly difficult to understand (1). For one person, it could indicate a serious problem or, for another, it could be a fluke, without any rhyme or reason. That is what makes it impossible to diagnose, or to use it to help diagnose other, possibly more serious afflictions. It is difficult to recreate in a laboratory setting, but, in recent years, it has been possible to induce the same feelings through hypnosis (2). Another problem is that it is only characterized by the feelings of eeriness and familiarity, which, as one knows, also can accompany a myriad of other medical problems.
I found it both interesting and surprising that certain situations can increase or lessen one’s chances of having one of the forms of déjà vu. I had always thought that déjà vu was something immutable that just occurred without any provocation, but now I see that it is something that is highly affected by various factors, such as mental conditions, mood, past memories. To me, déjà vu is the lint trap that catches all of the brain’s shattered memories, the thoughts that we are unable to place in a context or piece back together into a full remembrance of something that has occurred that was deemed as trivial or unimportant. My research has helped me understand why déjà vu exists and how it can vary from person to person, but it has not specifically helped me with my own frequent experiences of déjà vecu. I suppose the only way to try to understand my own situation, like all situations involving déjà vu, is to be highly aware of my surroundings, and to try to connect the eerie feelings with the ordinary fragments that helped create them.
- http://en.wikipedia.org/wiki/D%C3%A9j%C 3%A0_vu