Deja vu and deja vecu: from mysticism to neurobiology
Deja vu and deja vecu: from mysticism to neurobiology
Anonim

A few years ago, on a very ordinary day, something very unusual happened to me.

I was relaxing under a tree in a crowded park in east London when I suddenly felt dizzy and felt an incredibly strong sense of recognition. The people around me disappeared, and I found myself on a plaid picnic blanket in the middle of a field of tall golden wheat. The memory was rich and detailed. I heard ears rustling in a gentle breeze. The sun warmed my neck, and birds circled over my head.

It was a pleasant and incredibly vivid memory. The only problem was that it never happened to me. What I experienced was the ultimate manifestation of a very common psychic illusion: déja vu.

For us, memories are something sacred. One of the most fundamental doctrines of Western philosophy was laid down by Aristotle: he considered the newborn infant to be a kind of blank notebook that is filled in as the child grows and acquires knowledge and experience. Whether it's the ability to tie our shoelaces or the events of the first day of school, memories create that autobiographical map that allows us to navigate in the present. Songs from old TV ads, the name of the penultimate prime minister, the key phrase of the anecdote - memories are an integral part of the personality.

Most of the time, memory systems run quietly and discreetly in the background while we go about our daily activities. We take their effectiveness for granted. Until they fail.

For the past five years, I have suffered from epileptic seizures - the aftermath of a lemon-sized tumor growing in the right hemisphere of my brain and surgery to remove it. Before I was diagnosed, I looked perfectly healthy: I was in my early thirties and had no symptoms - until I woke up on the kitchen floor with bruises under my eyes from my first attack.

Seizures, or seizures, are the result of an unexpected electrical discharge in the brain. Usually they are preceded by a phenomenon called an "aura" - a kind of harbinger of the main attack. It can be of any length, up to several minutes. The manifestations of the aura in different patients are very different.

Some people experience synesthesia, a feeling of absolute bliss, or even an orgasm at the onset of an attack

Everything is far from so exciting for me: sudden changes in perspective, heart palpitations, anxiety and from time to time auditory hallucinations.

The English neurologist John Hughlings Jackson was the first to describe the epileptic aura: back in 1898, he noted that among its most characteristic manifestations are very vivid hallucinations, reminiscent of memories and often accompanied by a feeling of déjà vu. “Scenes from the past are coming back,” one of the patients told him. “It’s like I’m in some strange place,” said another.

Without a doubt, the most significant sign of my aura is the amazing feeling that I have experienced this very moment before, although this has never happened.

During the most intense attacks and for about a week after them, this feeling is so convincing that I spend a lot of energy to distinguish between what I have experienced and what I have dreamed, weed out real memories from hallucinations and the fruits of my imagination

Before I got epilepsy, I don't remember experiencing déjà vu with any regularity. Now I experience them - with varying degrees of intensity - up to ten times a day, either as part of an attack or apart from it. I cannot find any regularities that would explain when and why these episodes will appear, I only know that they usually last no longer than a second, and then disappear.

Many of the approximately 50 million people with epilepsy experience long-term memory loss and psychiatric problems. And it's hard for me not to worry about whether my confusion of fact and fiction will sooner or later lead to insanity. In trying to better understand déjà vu, I hope to ensure to myself that I can always return to reality from this “strange place”.

In Catch-22, Joseph Heller described déjà vu as "the strange, mystical feeling that you've experienced a similar situation at some point in the past." Peter Cook in a magazine column put it in his own way: "Each of us at some point experienced deja vu - the feeling that all this has already happened, has already happened, has already happened."

Déjà vu (from French for "already seen") is one of several related memory failures. According to 50 different surveys, approximately two-thirds of healthy people have ever experienced déjà vu. Most do not pay attention to it, considering it just a strange curiosity or not very interesting cognitive illusion.

If deja vu is instantaneous and transient, then the experience of deja vecu (“already experienced”) is much more disturbing. Deja Vecu is the strong feeling that you have experienced the entire sequence of current events sometime before

The hallmark of ordinary déjà vu is the ability to understand that this is not reality. When faced with déjà vu, the brain performs a kind of test of all senses in search of objective evidence of previous experience, and then discards déja vu as the illusion it is. It is known that people with deja vecu completely lose this ability.

Professor Chris Moulin, one of the leading experts in déjà vu, describes a patient he met at a memory impairment clinic in Bath, England. In 2000, Moulin received a letter from a local family doctor describing an 80-year-old retired engineer under the code name AKP. Due to the gradual death of brain cells due to dementia, AKP suffered from deja vecu, a chronic, incessant deja vu.

AKP stated that it gave up watching TV and reading newspapers because it knew what was going to happen. “His wife described him as someone who felt like everything in his life had already happened,” says Moulin, who now works at the Laboratory of Psychology and Neurocognitive Science at the National Center for Scientific Research in Grenoble. The AKP refused to go to the hospital because he thought he had already gone there, although in reality it had not. When he was first introduced to Moulin, he said he was even able to describe specific details of their previous encounters.

AKP partially retained the ability to critically assess itself. “His wife asked how he knew what the TV program would be about if he had never watched it before,” says Moulin. - To this he replied: “How do I know? I have memory problems."

In the park that day, the vision of a picnic blanket and a wheat field faded when the emergency doctor shook me by the shoulder. Even though my memories were illusory, they felt as real as any real memory. According to Moulin's classification, with this form of "already tested" experience, the image is somehow filled with a sense of reality. “We assume that déjà vu is triggered by a sense of recognition,” he says. "Apart from the simple feeling that something has to do with the past, this phenomenon also has phenomenological characteristics, that is, it seems like a real memory."

Moulin's other patients showed so-called anosognostic manifestations: they either did not understand what state they were in, or they could not immediately distinguish between memory and fantasy. “I spoke with one woman who said her déjà vu were so strong that they were no different from real memories of her own life for her,” Moulin told me.- Some of what happened to her was quite fantastic: she remembered flying in a helicopter. It was difficult for her to deal with these memories, because she had to spend a lot of time to find out whether this or that event actually happened."

After the first meeting with AKP, Moulin became interested in the reasons for déjà vu and how subjective feelings can interfere with the daily processes of memory functioning. Finding that there was very little reliable literature describing cases of déjà vu, Moulin and his colleagues at the Language and Memory Laboratory of the Institute of Psychological Sciences at the University of Leeds began studying epileptics and other patients with severe memory impairments in order to draw conclusions about the experience "already experienced" in healthy brain and find out what deja vu means for the work of consciousness.

They immediately faced a problem: the déjà vu experience can be so short-lived and so transient that it is almost impossible to recreate it in a clinic setting. That is, the task that faced them was akin to trying to catch lightning in a bottle.

Emile Buarak lived in the 19th century and studied telekinesis and parapsychology, was interested in clairvoyance - this was typical of the Victorian era. In 1876, he described for a French philosophical journal his experience of a visit to an unfamiliar city, accompanied by a sense of recognition. Buarak was the first to introduce the term "deja vu" into circulation. He theorized that the sensation was caused by a kind of mental echo or ripple: the new experience simply brought about a forgotten memory.

Although this theory is still considered quite convincing, subsequent attempts to explain déjà vu became more extravagant.

Sigmund Freud's The Psychopathology of Everyday Life, published in 1901, is best known for exploring the nature of Freudian slips, but it also deals with other memory defects. The book describes the "already experienced" feelings of one woman: when she first entered her friend's house, she felt that she had already been there before, and claimed that she knew in advance the sequence of all the rooms.

Her feelings today would be called a deja visit, or "already visited." Freud explained the deja of his patient's visit as a manifestation of suppressed fantasy, which only came to light in a situation that reminded the woman of a subconscious desire

This theory, too, was not completely discredited, although in his typical manner Freud suggested that déjà vu could be traced back to fixation on the mother's genitals - the only place for which, he wrote, "it is safe to say that the person has been there before."

The accepted scientific definition of déjà vu was formulated in 1983 by the South African neuropsychiatrist Vernon Neppé; according to him, déjà vu is "any subjectively inadequate sensation of recognition in the present sensation of an indefinite moment from the past."

Neppe identified 20 different forms of "already tried" experience. Not all of them are related to vision: one of Chris Moulin's patients was blind from birth, but claimed to have deja vu, and Neppe's descriptions include such phenomena as deja senti ("already felt") and deja antandu ("already heard ")

The Freudian understanding of déja vu as a purely psychological phenomenon, and not caused by neurological failures, unfortunately led to the fact that explanations of "already experienced" experience become absurdly mystical.

The Gallup Institute, conducting a 1991 poll on attitudes towards déjà vu, ranked it on a par with questions about astrology, the paranormal, and ghosts. Many consider déjà vu to be outside of everyday cognitive experience, and abnormalities of all sorts claim to be irrefutable evidence of telepathy, alien abductions, psychokinesis, and past lives.

It's easy for me to be skeptical about these explanations, especially the last one; but these alternative theories mean that there is very little mainstream science focus on déjà vu. It is only now, almost 150 years after Emile Bouarak coined the term, that researchers like Chris Moulin are beginning to understand what actually causes system errors in the brain's "wet computer", as neurologist Reed Montague has so emphatically called it.

The hippocampus is a very beautiful thing. In mammals, the two hippocampus are symmetrically located in the lower part of the brain. The hippocampus in ancient Greek means "seahorse", and it was named so because it resembles a curled seahorse, which stretches with its delicate tail to a long muzzle. And only in the last 40 years have we begun to understand why these sensitive structures are needed.

Scientists used to think that all memories were neatly stacked in one place, like documents in a drawer. This scientific consensus was disproved in the early seventies: neurocognitive professor Endel Tulving proposed a new theory according to which memories belong to one of two different groups

What Tulving called "semantic memory" are general facts that do not affect the individual, since they have nothing to do with personal experience. "Episodic" memory consists of memories of life events and personal impressions. The fact that the Natural History Museum is located in London belongs to semantic memory. And the case when I went there at the age of eleven with a class is a fact of episodic memory.

Thanks to advances in neuroimaging, Tulving established that episodic memories are created as small messages of information at different points in the brain, and then assembled into a coherent whole. He believed that this process is akin to reliving these events. “To remember is to travel through time in your mind,” he said in 1983. "That is, in a sense, to relive the events that happened in the past."

Many of these signals come from the hippocampus and its surrounding area, suggesting that the hippocampus is the brain's librarian, responsible for receiving information already processed by the temporal lobe, sorting it out, indexing it, and storing it as an episodic memory. …

Just as the librarian arranges books by topic or by author, so the hippocampus identifies common features in memories

He can use analogies or similarities, for example, by grouping all the memories of different museums in the same place. These similarities are then used to link the content of episodic memories so that they can be retrieved in the future.

Unsurprisingly, in patients with epilepsy that causes deja vu, seizures start in the part of the brain that is most closely associated with memory. It is also quite natural that epilepsy of the temporal lobe affects episodic memory more than semantic memory. My own seizures start in the temporal lobe, the part of the cerebral cortex behind the ear and is primarily responsible for processing input from the senses.

In his book Experience of Déjà Vu, Professor Alan S. Brown offers thirty different explanations for déjà vu. If you believe him, each of these reasons separately can cause a sense of déjà vu. In addition to biological disorders such as epilepsy, Brown writes that stress or fatigue can be the cause of déjà vu.

My déjà vu experience began during a long recovery period from brain surgery. I was constantly in four walls, floating between semi-conscious states: mostly I was under sedatives, sleeping or watching old films.This twilight state during recovery could make me more sensitive to the "already experienced" experience due to fatigue, excess sensory input, and rest to the point of coma. But my case was clearly unusual.

Brown is a proponent of the so-called split perception theory. This theory was first described by Dr. Edward Bradford Titchener in the thirties; we are talking about cases when the brain does not pay enough attention to the surrounding world

Titchener used the example of a man who is about to cross a busy street but is distracted by a shop window. “When you end up crossing the road,” he wrote, “you think:“I just crossed it”; your nervous system has severed two phases of the same experience, and the second phase seems to be a repetition of the first."

For most of the past century, the idea that déjà vu arises in this way has been considered compelling. Another common explanation came from Dr. Robert Efron, who worked at Boston's Veterans' Hospital. In 1963, he suggested that déjà vu might be caused by some kind of error in data processing: he believed that the temporal lobe of the brain collects information about events, and then adds to them something like a date that determines when they occurred.

Efron believed that déjà vu is the result of the lag of this time marking from the moment of visual perception: if the process takes too long, the brain thinks that the event has already happened before.

But Alan Brown and Chris Moulin agree that the more likely cause of déjà vu is the work of the hippocampus to catalog and cross-reference memories based on similarities.

“I believe that seizure-related deja vu is caused by spontaneous activity in the part of the brain that is responsible for assessing similarity,” says Brown. According to him, this may be happening in the area surrounding the hippocampus, and most likely on the right side of the brain. Exactly where I have a lemon-shaped hole.

To test Alan Brown's theory that déjà vu is triggered by an error in the grouping of memories by the hippocampus, Brown and Elizabeth Marsh conducted an experiment in the Department of Psychology and Neurology at Duke University. At the beginning of the experiment, students at Duke University and Southern Methodist University in Dallas were briefly shown photographs of places - dorm rooms, libraries, auditoriums - on two campuses.

A week later, the students were shown the photographs again, but new ones were added to the original set. When asked if they were in all the places in the photo, some students answered yes, even if the photo showed an unfamiliar campus.

Many university buildings are similar; thus, by sowing a seed of doubt about where the students actually went, Brown and Marsh were able to conclude that just one element of an image or experience might be enough for the brain to remember something familiar

Chris Moulin and Dr. Akira O'Connor, his colleague at the University of Leeds, have already replicated déjà vu in a laboratory in 2006. The purpose of their work was to study the process of retrieving memories. To do this, they examined the difference between how the brain registers information about the experience and how it then checks the data from all senses to see if this situation has really happened before.

Moulin suggests that déjà vu is triggered by “a brief, exaggerated recognition response that occurs in moments of panic or stress, or is reminiscent of something else. There is a very excitable part of the brain that just constantly scans everything around and looks for the familiar,”he says. "With déjà vu, additional information comes in later that this situation may not be familiar."

Moulin came to the conclusion that the brain retrieves memories within a kind of spectrum: at one end of it there is an absolutely correct interpretation of visual memory, and at the other end there is a constant sense of deja vechu. Somewhere in between these extremes is deja vu: not as serious as deja vecu, but not as flawless as normal brain function.

Moulin also suggests that somewhere in the temporal lobe there is a mechanism that controls the process of remembering

Problems with this area can lead to the patient completely losing the ability to understand that new events are taking place in his life, and will forever remain trapped in his own memory, twisted like a Mobius strip.

But why do ordinary healthy people experience the same?

Brown suggests that déjà vu in healthy people occurs a few times a year at most, but can be exacerbated by external conditions. “Most of the time people experience this feeling when they are indoors, during leisure or recreation, with friends,” he says. "Fatigue or stress often accompanies this illusion." He says that the feeling of déjà vu is relatively short-lived (10 to 30 seconds), occurs more often in the evenings than in the mornings, and more often on weekends than on weekdays.

Some researchers believe there is a link between the ability to remember dreams and the chances of experiencing déjà vu

Brown suggests that while déjà vu occurs with equal frequency in women and men, it is more common in young people who travel a lot, earn more money, and whose political and social views are closer to liberal ones.

“There are some pretty compelling explanations for this,” he said. - People who travel more are more likely to face a new situation that may seem strangely familiar to them. People with liberal views are more likely to admit that they are faced with unusual mental phenomena, and are more willing to understand them. People with a conservative worldview are more likely to avoid admitting that something incomprehensible is happening to their psyche, because this can serve as a sign of mental imbalance.

The question of age is a mystery, because usually memory starts doing strange things as we age, and not vice versa. I would suggest that young people are more open to different sensations and more attentive to unusual manifestations of their psyche."

One of the first detailed studies of déjà vu was conducted in the forties by a student at New York University, Morton Leeds. He kept an incredibly detailed diary of his frequent experiences of "already experienced" and described 144 episodes in a year. One of them, he said, was so intense that he felt sick.

I have experienced something similar after my recent attacks. The sensation of constant déjà vu is not necessarily physiological; rather, it is a kind of mental pain that can cause physiological nausea. Dreams burst into the normal stream of thought, conversations seem to have taken place, and even things as trivial as a cup of tea or a newspaper headline seem familiar. Sometimes I have the feeling that I am leafing through a photo album in which the same photo is repeated endlessly.

Some sensations are easier to discard than others. Getting closer to understanding what triggers déjà vu means for me to bring closer the end of the most persistent episodes of "already experienced", with which it is most difficult to live.

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