Deja vu and LSD

No, you haven't read this déjà vu story before

By Sandee LaMotte, CNN Updated 1251 GMT (2051 HKT) January 8, 2016

Story highlights   

Two-thirds of us experience déjà vu at least once in our lives It's more common among the young, well-traveled and more educated People who remember their dreams are more likely to have déjà vu (CNN)We know the feeling (or at least 66% of us do). Déjà vu is the belief you've been here or done that before, when you know there's absolutely no way you could have. The phrase déjà vu is French, meaning "already seen."

But we know less about why we have the feeling. Is déjà vu evidence of a past life, an out of body experience or just a good old neural misfire?

Sponsor Content

Laura battled cervical cancer three times. Here’s her story Laura Fletcher, a three-time survivor of recurrent HPV-linked cervical cancer, shares herstory to raise awareness of HPV and related cancers.

Content provided by MSD

Most researchers who study this area of the brain vote for the last option, and they are busy trying to find all the reasons why.

Who gets déjà vu?

About two-thirds of us experience déjà vu at least once in our lives, experts say. While there's no gender difference when it comes to the phenomenon, age does seem to matter. Déjà vu episodes drop dramatically in older adults; in fact, most reports come from people between age 15 and 25, leading some to wonder if déjà vu is connected to brain development. We now know the brain isn't fully formed until at least age 25, maybe even later.

Déjà vu is also most common in people with higher education and socioeconomic class, and those who watch more movies and travel often. If déjà vu is all about familiarity-based recognition, there's some logic to these statistics: Travel is most common among those with higher incomes, and traveling provides more opportunities to see new physical locations that might trigger a sense of familiarity, especially if those locations may have appeared in a previously viewed movie scene.

"Memory is far from perfect. We simply fail to recall everything that we encounter in day-to-day life," explained déjà vu researcher Anne Cleary. "However, just because something fails to be recalled doesn't mean that the memory isn't still 'in there' somewhere; often it is, and it is just failing to be accessed. These types of memories might be what drive the sense of familiarity that presumably underlies déjà vu."

Research also shows déjà vu is more likely to happen if a person is under pressure or fatigued.

Perhaps when we're tired, stressed or distracted we only recall a fraction of an event, just enough to trigger a sense of familiarity.

A 2010 study found those of us who frequently remember our dreams seem to have more déjà vu experiences. Dreams are notorious for being less than faithful to reality. Add that to the already fallible memory system of our brains, and you can see why the two might interact to create a feeling of familiarity; maybe you dreamed it, or something like it.

There's actually a term for dream déjà vu: déjà reve, French for "dreamed before." About 86% of college students surveyed as part of a study report reliving events they remember from dreams. Cleary said she believes this might happen when you dream about something you've experienced, but later only remember the dream, not the event itself.

The brain on déjà vu Since having a déjà vu experience is unpredictable, it has been tough to study. That's why some researchers are focused on the brains of patients with a certain form of epilepsy: specifically, those who often experience déjà vu during the "auras" that occur right before a seizure.

"The epilepsy patients whose seizures tend to trigger déjà vu have generally been patients whose seizures originate in the medial temporal region of the brain," said Cleary. "This same area of the brain is involved in memory."

In the medial temporal lobe of the brain sits the rhinal cortex, which helps us recognize that something is familiar. Close by is the hippocampus, responsible for new memory storage. Not far away is the amygdala, in charge of our emotions, which can drive memory storage and retrieval.

By sending an electric current into the medial temporal region of the brain, researchers have been able to trigger déjà vu experiences in epileptic patients and map brain activity. They found that even though the hippocampus is responsible for memory, it's easier to induce déjà vu via the rhinal cortex, the portion of the brain responsible for feelings of familiarity. Yet all three brain structures appear to be active during the episode.

Patients in these studies report two types of seizure experiences: One involves a feeling of déjà vu familiarity, the other a more vivid and complete recollection of an event from the past. That's known as déjà vécu', or "already lived." It has been suggested the two may fall on a continuum, with déjà vu being a sort of low-level form of failed recollection.

Harnessing déjà vu into precognition?

Cleary, a cognitive psychologist Colorado State University, is using today's technology to recreate the experience of déjà vu. She has created a 3-D virtual village she calls "Deja Ville," based on the popular Sims 2 game, and is using it to explore the concept of Gestalt familiarity, the arrangement of objects within a scene.

"For every original scene created, we created another, different scene that mapped onto that original scene in its spatial configuration -- the configuration of elements on the grid," said Cleary. "For example, if the original scene was a courtyard with a potted tree in the middle, surrounded by flower beds and hanging pots on the courtyard walls, the corresponding similar scene might be a museum with a statue in the middle where the potted tree had been, surrounded by rugs in the same configuration as the flower beds, and candelabra in the same configuration as the hanging pots."

She also presented the subjects completely novel scenes, which didn't have any similar elements that might be "mapped" and recognized. She found there was a greater likelihood of reported déjà vu experiences when subjects failed to recall one of the previously seen mapped scenes.

She's now using the 3-D model to see if the memories that underlie a déjà vu experience can help us predict what happens next, serving as a form of "precognition."

"It's conceivable that a previous experience that exists in memory but that fails to be retrieved might not only produce a sensation of déjà vu upon encountering a highly similar situation, but also produce a sense of how the current event is supposed to unfold," explained Cleary, "such as which direction to turn next within the scene."

Could those insights give déjà vu a reason for its existence?

"Even when we fail to retrieve a memory," said Cleary, "our brains might have a way of signaling to us that there is possibly a relevant memory in there somewhere. That signal might be useful in that it can

prompt us to keep searching our memory for whatever it is that is in there that might be relevant to the current situation."

Déjà vécu: When déjà vu becomes your reality One drab afternoon a few years ago something very unusual happened to me.

I was lounging under a tree in a packed east London park when I experienced a sudden feeling of vertigo, followed immediately by an overwhelming and intense sense of familiarity.

The people around me vanished and I found myself lying on a tartan picnic blanket amid a field of high golden wheat. The memory was rich and detailed. I could hear the sway of the wheat ears as a gentle breeze brushed through them. I felt warm sunlight on the back of my neck and watched as birds wheeled and floated above me.

It was a pleasant and extremely vivid recollection. The problem was that it never actually happened.

What I was experiencing was an extreme form of a very common mental illusion: déjà vu.

Living with persistent déjà vu For the past five years I have been suffering epileptic seizures resulting from the growth and eventual removal of a lemon-sized tumour from the right-hand side of my brain. Before my diagnosis I appeared fit and healthy: I was in my mid-30s and displayed absolutely no symptoms. Until, that is, the afternoon that I woke up on the kitchen floor with two black eyes after suffering my first recorded seizure.

No, you haven't read this déjà vu story before Seizures, or fits, occur after an unanticipated electrical discharge in the brain. They are usually preceded by something called an 'aura', a sort of minor foreshock lasting anything up to a couple of minutes before the main event begins. The nature of this aura differs greatly from patient to patient.

Some people experience synaesthesia, extreme euphoria and even orgasm at the onset of a seizure.

My own aren't nearly as exciting-sounding, being distinguished by sudden shifts in perspective, a rapidly increased heart rate, anxiety, and the occasional auditory hallucination.

By far the most significant trait of my aura is the striking sense of having lived through that precise moment before at some point in the past -- even though I never have. During my most intense seizures, and for a week or so afterwards, this feeling of precognition becomes so pervasive that I routinely struggle to discern the difference between lived events and dreams, between memories, hallucinations and the products of my imagination.

I don't remember déjà vu happening with any kind of regularity before the onset of my epilepsy. Now it occurs with varying degrees of magnitude up to ten times a day, whether as part of a seizure or not. I can find no pattern to explain when or why these episodes manifest themselves, only that they usually last for the length of a pulse before vanishing.

Many of the estimated 50 million people in the world with epilepsy experience long-term memory decline and psychiatric problems. And it's hard for me not to worry whether the blurring of fact and fiction that I experience might one day engender a kind of mania.

Exploring the déjà experience Taken from the French for 'already seen', déjà vu is one of a group of related quirks of memory.

Research from 50 different surveys suggests that around two-thirds of healthy people have experienced déjà vu at one time or another. For the majority, it is dismissed as a curiosity or a mildly interesting cognitive illusion.

This is your brain on LSD, literally While déjà vu is instantaneous and fleeting, déjà vécu (already lived) is far more troubling. Unlike déjà vu, déjà vécu involves the sensation that a whole sequence of events has been lived through before.

What's more, it lacks both the startling aspect and instantly dismissible quality of déjà vu.

A defining feature of the normal déjà vu experience is the ability to discern that it isn't real. On encountering déjà vu, the brain runs a sort of sense check, searching for objective evidence of the prior experience and then disregarding it as the illusion that it is. People with déjà vécu have been known to lose this ability completely.

Professor Chris Moulin, one of the foremost experts on the déjà experience, describes a patient he encountered while working at a memory clinic at a hospital in Bath, England. In 2000, Moulin received a letter from a local GP referring an 80-year-old former engineer known as AKP. As a result of gradual brain-cell death caused by dementia, AKP was now suffering from chronic and perpetual déjà vu: déjà vécu.

AKP claimed that he had given up watching television or reading the newspaper because he knew what was about to happen. "His wife said that he was someone who felt as though everything in his life had happened before," says Moulin, now at the Laboratoire de Psychologie et NeuroCognition CNRS in Grenoble. AKP was resistant to the idea of visiting the clinic because he felt as though he'd already been there, despite the fact that he never had. On being introduced to Moulin for the first time, the man even claimed to be able to give specific details of occasions that they had met before.

New brain map identifies 97 previously unknown regions AKP did retain some self-awareness. "His wife would ask him how he could know what would happen in a television programme if he'd never seen it before," says Moulin, "to which he would respond, 'How would I know? I have a memory problem.'"

On that day in the park, my vision of the picnic blanket and the wheat field disappeared when a paramedic began to shake my shoulder. Despite the fact that my memories had been hallucinations, they still felt as valid as any truly autobiographical memory. Moulin classes this as a form of déjà experience in which an image is somehow imbued with a sense of reality.

"Our feeling is that déjà vu is caused by a sense of familiarity," he says. "Rather than just feeling like something has a feeling of 'pastness' about it, something comes to mind that has a phenomenological characteristic, so that it appears to be a real reminiscence."

After his first encounter with AKP, Moulin began to become interested in the causes of déjà vu and how subjective feelings can interfere with day-to-day memory processes. Discovering that there was very little credible literature describing the causes of déjà vu, Moulin and colleagues at the Language and Memory Lab at the Institute of Psychological Sciences, University of Leeds, began to study epileptics and other sufferers of profound memory defects in order to draw conclusions about déjà experiences in the healthy brain and explore what déjà vu means for the workings of consciousness generally.

They were faced with an immediate problem: déjà vu experiences can be so transitory and short-lived that they are almost impossible to recreate in clinical conditions. The job that they faced, then, was one of trying to catch lightning in a bottle.

The causes of déjà vu In his book The Déjà Vu Experience, Professor Alan S Brown offers 30 different explanations for déjà vu. According to him, any one alone may be enough to trigger a déjà experience. As well as a biological dysfunction like epilepsy, Brown writes that stress or tiredness could cause déjà vu.

Brown is also a proponent of what is called the divided perception theory. First described in the 1930s

by Dr Edward Bradford Titchener, divided perception refers to the times when the brain isn't quite paying enough attention to its surroundings. Titchener used the example of a person about to cross a busy street before being distracted by a shop window display. "As you cross," he wrote, "you think, 'Why, I crossed this street just now'; your nervous system has severed two phases of a single experience, and the latter appears as a repetition of the earlier."

For much of the last century this idea was accepted as a plausible trigger of déjà vu. Another common explanation was one offered by a doctor working at the Boston veterans' hospital. In 1963 Robert Efron suggested that déjà vu could be caused by a sort of processing error: he believed that brains were responsible for assimilating events through the temporal lobe before then adding a sort of timestamp to them to determine when they happened.

Efron saw déjà vu as resulting from the lag between seeing and adding that timestamp: if the process took too long, the brain would think that an event had already happened.

But Alan Brown and Chris Moulin both agree that the way that the hippocampus indexes memories by cross-referencing them according to familiarity is a more likely cause of déjà vu.

"My belief is that a per-seizure déjà vu experience is triggered by spontaneous activity in that area of the brain that handles familiarity evaluations," says Brown. Probably, he says, in the area surrounding the hippocampus, and most likely on the right side of the brain. The precise point at which I have a lemon-shaped hole.

Brown suggests that déjà vu happens to healthy people only a few times a year at most, but can be stimulated by environmental factors. "People experience it mainly when they are indoors," he says, "doing leisure activities or relaxing, and in the company of friends; fatigue or stress frequently accompany the illusion." He says that déjà vu is relatively brief (10 to 30 seconds), and is more frequent in the evening than in the morning, and on the weekend than on weekdays.

Some researchers claim a connection between the ability to remember dreams and the likelihood of experiencing déjà vu. In his work, Brown suggests that although déjà vu occurs equally in women and men, it is more common in younger people, those that are well-travelled, earn higher incomes and whose political and social outlooks are more aligned to the liberal.

"There are some plausible explanations for this," he tells me. "People who travel more have more opportunities to encounter a new setting that they may find strangely familiar. People with liberal beliefs may be more likely to admit to having unusual mental experiences and willing to figure them out. A conservative mindset would likely avoid admitting to having strange mental events, as they might be seen as a sign that they are unstable.

"The age issue is a puzzle because memory usually gets more quirky as we age, rather than the other way around. I would guess that young people are more open to experiences and more in touch with unusual mental happenings."

One of the first comprehensive studies of déjà vu was conducted in the 1940s by a New York undergraduate student called Morton Leeds. Leeds kept an extraordinarily detailed diary of his frequent déjà experiences, noting 144 episodes over the course of a year. One of these episodes, he wrote, was "so strong that it almost nauseated me".

Following my most recent seizures I've experienced something similar. The shock of repeated déjà vu isn't physical, necessarily, but instead causes a kind of psychic pain that can feel physically sickening.

Dream images suddenly interrupt normal thoughts. Conversations seem to have already taken place.

Even banal things like making a cup of tea or reading a particular newspaper headline seem familiar. It feels occasionally like I'm flicking through a photo album containing nothing but the same picture reproduced endlessly.

Some of these sensations are easier to dismiss than others. Coming closer to finding an answer to what causes déjà vu also means approaching a kind of resolution for my more persistent déjà episodes, the ones that are the hardest of all to live with.

The night before completing this piece I had another seizure. The deadline had clearly been on my mind, as I suddenly had an intense memory of sitting down to write these closing sentences. When I regained my composure enough to read the finished article the next day, there was nothing here but blank space. It was another illusion. Now I'm actually typing this conclusion. It is, to borrow a famous solecism, like déjà vu all over again.

This is an edited version of an article that was first published by Wellcome on Mosaic. It is republished here under a Creative Commons licence.

Copyright 2015 The Wellcome Trust. Some rights reserved.

This is your brain on LSD, literally (CNN)Scientists have for the first time visualized the effects of LSD on the human brain.

Using brain scanning and other techniques, researchers at Imperial College London were able to show what happens when someone takes the popular (and illegal) psychedelic, scientific-name Lysergic acid diethylamide.

The drug, as well as a placebo, was given to 20 healthy volunteers with previous experience taking psychedelics. Their brains were then imaged inside an fMRI scanner to visualize their brain activity.

"Under normal conditions, information from our eyes is processed in a part of the brain at the back of the head called the visual cortex," the researchers said in a statement.

"However, when the volunteers took LSD, many additional brain areas -- not just the visual cortex -contributed to visual processing."

Why a song gets stuck in your head 01:32

Images of the brain under a hallucinogenic state showed almost the entire organ lit up with activity.

"We see this explosion of communication," said Dr. Robin Carhart-Harris, from the Department of Medicine at Imperial, who led the study.

The visual cortex became much more active with the rest of the brain, and blood flow to visual regions also increased, which the researchers believe correlates with the hallucinations reported by volunteers.

READ: Why your brain works against your best intentions "Our results suggest that this effect underlies the profound altered state of consciousness that people often describe during an LSD experience," Carhart-Harris added.

"It is also related to what people sometimes call 'ego-dissolution,' which means the normal sense of self is broken down and replaced by a sense of reconnection with themselves, others and the natural world. This experience is sometimes framed in a religious or spiritual way -- and seems to be associated with improvements in well-being after the drug's effects have subsided."

Rethinking LSD First manufactured in Switzerland in 1938 for the treatment of psychiatric disorders, LSD's subsequent popularity as a recreational psychedelic saw it criminalized in much of the world.

In both the United States and United Kingdom, LSD is a schedule 1 drug, the most restrictive classification.

Ever had deja vu? Ever had deja vu? 02:08 READ: Test whether you have a happy brain However, in recent years, many scientists and others have advocated for a rethink of the drug's status, particularly its use for treating psychiatric disorders, alcoholism and depression.

The team at Imperial currently have clinical trials underway investigating the potential for psilocybin -the active chemical inside magic mushrooms -- to treat depression, but believe LSD could be useful for disorders that are more difficult to treat, such as addiction.

"Conditions like addiction and alcohol dependence can be stubborn ... you might need something more potent to really make in-roads to conditions like [these]," said Carhart-Harris.

'Love drug' found in chocolate 01:26

Professor David Nutt, former chairman of the UK Advisory Council on the Misuse of Drugs and senior researcher on the study, has long argued for more research into how psychedelics affect the brain and how they could be put to medical uses.

"Scientists have waited 50 years for this moment -- the revealing of how LSD alters our brain biology," Nutt said.

"For the first time we can really see what's happening in the brain during the psychedelic state, and can better understand why LSD had such a profound impact on self-awareness in users and on music and art. This could have great implications for psychiatry, and helping patients overcome conditions such as depression."

READ: How to solve a 300-year old maths puzzle Amanda Feilding, Director of the Beckley Foundation, which took part in the study, said: "We are finally unveiling the brain mechanisms underlying the potential of LSD, not only to heal, but also to deepen our understanding of consciousness itself."

Meera Senthilingam contributed to this report.