Spotless Mind: MIT Neuroscientists Place False Memories And Reverse Negative Associations


Eternal Sunshine of the Spotless Mind is a 2004 American romantic science-fiction comedy-drama film about an estranged couple who have each other erased from their memories. Pretty fancy stuff, for a sci-fi romantic comedy. There’s nothing we can do to change the past, however new research from MIT, suggests there soon may be a way to change how we feel about it.

What follows will knock you silly, upending every single concept of storytelling that you’re probably used to. Neuroscientists have developed a technique to reverse the mechanism by which memories become associated with positive or negative emotions. Published in the August 27 issue of Nature, the “optogenetic” technique uses light to manipulate brain cells and control neuron activity.

Most memories have some kind of emotion associated with them: Recalling the week you just spent at the beach probably makes you feel happy, while reflecting on being bullied provokes more negative feelings. A new study from MIT neuroscientists reveals the brain circuit that controls how memories become linked with positive or negative emotions. Furthermore, the researchers found that they could reverse the emotional association of specific memories by manipulating brain cells with optogenetics — a technique that uses light to control neuron activity.

The findings, described in the Aug. 27 issue of Nature, demonstrated that a neuronal circuit connecting the Hippocampus and the Amygdala plays a critical role in associating emotion with memory. This circuit could offer a target for new drugs to help treat conditions such as post-traumatic stress disorder, the researchers say.

“In the future, one may be able to develop methods that help people to remember positive memories more strongly than negative ones,” says Susumu Tonegawa, the Picower Professor of Biology and Neuroscience, director of the RIKEN-MIT Center for Neural Circuit Genetics at MIT’s Picower Institute for Learning and Memory, and senior author of the paper.

The paper’s lead authors are Roger Redondo, a Howard Hughes Medical Institute postdoc at MIT, and Joshua Kim, a graduate student in MIT’s Department of Biology.


 At its core, Eternal Sunshine of the Spotless Mind could have been just another love story. Refracted through Kaufman’s wonderfully weird prism, it’s something truly memorable. It goes by like a fevered dream of love, but one you remember vividly, with profound pleasure

Shifting memories

All of us already generate false memories as human memory constantly adapts and molds itself to fit the world. Our imagination can trick us into thinking we’ve done something we’ve never really done and lead us to create such compelling, illusory memories. The reason our memories are so malleable is because there is simply too much information to take in. Our perceptual systems aren’t built to notice absolutely everything in our environment. We take in information through all our senses but there are gaps. So when we remember an event, what our memory ultimately does is fills in those gaps by thinking about what we know about the world. Reporting in Science, they say it could one day shed light into how false memories occur in humans.

Memories are made of many elements, which are stored in different parts of the brain. A memory’s context, including information about the location where the event took place, is stored in cells of the Hippocampus, while emotions linked to that memory are found in the Amygdala. Previous research has shown that many aspects of memory, including emotional associations, are malleable. Psychotherapists have taken advantage of this to help patients suffering from depression and post-traumatic stress disorder, but the neural circuitry underlying such malleability is not known.

In this study, the researchers set out to explore that malleability with an experimental technique they recently devised that allows them to tag neurons that encode a specific memory, or engram. To achieve this, they label hippocampal cells that are turned on during memory formation with a light-sensitive protein called channelrhodopsin. From that point on, any time those cells are activated with light, the mice recall the memory encoded by that group of cells.

Last year, Tonegawa’s lab used this technique to implant, or “incept,” false memories in mice by reactivating engrams while the mice were undergoing a different experience. In the new study, the researchers wanted to investigate how the context of a memory becomes linked to a particular emotion. First, they used their engram-labeling protocol to tag neurons associated with either a rewarding experience (for male mice, socializing with a female mouse) or an unpleasant experience (a mild electrical shock). In this first set of experiments, the researchers labeled memory cells in a part of the Hippocampus called the Dentate Gyrus.

Two days later, the mice were placed into a large rectangular arena. For three minutes, the researchers recorded which half of the arena the mice naturally preferred. Then, for mice that had received the fear conditioning, the researchers stimulated the labeled cells in the Dentate Gyrus with light whenever the mice went into the preferred side. The mice soon began avoiding that area, showing that the reactivation of the fear memory had been successful. The reward memory could also be reactivated: For mice that were reward-conditioned, the researchers stimulated them with light whenever they went into the less-preferred side, and they soon began to spend more time there, recalling the pleasant memory.

A couple of days later, the researchers tried to reverse the mice’s emotional responses. For male mice that had originally received the fear conditioning, they activated the memory cells involved in the fear memory with light for 12 minutes while the mice spent time with female mice. For mice that had initially received the reward conditioning, memory cells were activated while they received mild electric shocks.

Next, the researchers again put the mice in the large two-zone arena. This time, the mice that had originally been conditioned with fear and had avoided the side of the chamber where their Hippocampal cells were activated by the laser now began to spend more time in that side when their Hippocampal cells were activated, showing that a pleasant association had replaced the fearful one. This reversal also took place in mice that went from reward to fear conditioning.

Altered connections

The researchers then performed the same set of experiments but labeled memory cells in the Basolateral Amygdala, a region involved in processing emotions. This time, they could not induce a switch by reactivating those cells — the mice continued to behave as they had been conditioned when the memory cells were first labeled. This suggests that emotional associations, also called valences, are encoded somewhere in the neural circuitry that connects the Dentate Gyrus to the Amygdala, the researchers say. A fearful experience strengthens the connections between the Hippocampal Engram and fear-encoding cells in the Amygdala, but that connection can be weakened later on as new connections are formed between the Hippocampus and Amygdala cells that encode positive associations.

“That plasticity of the connection between the Hippocampus and the Amygdala plays a crucial role in the switching of the valence of the memory,” Tonegawa says.

These results indicate that while Dentate Gyrus cells are neutral with respect to emotion, individual Amygdala cells are precommitted to encode fear or reward memory. The researchers are now trying to discover molecular signatures of these two types of Amygdala cells. They are also investigating whether reactivating pleasant memories has any effect on depression, in hopes of identifying new targets for drugs to treat depression and post-traumatic stress disorder.


Eternal Sunshine of the Spotless Mind is the second feature from director Michel Gondry (Human Nature) re-teaming with screenwriter Charlie Kaufman for this off-the-wall romantic comedy. Jim Carrey stars as Joel Barish, a man who is informed that his ex-girlfriend Clementine (Kate Winslet) has had her memories of their relationship erased from her brain via an experimental procedure performed by Dr. Mierzwiak (Tom Wilkinson). Not to be outdone, Joel decides to have the same procedure done to himself.

Unreliable memory

Just like in mice, our memories are stored in collections of cells, and when events are recalled we reconstruct parts of these cells – almost like re-assembling small pieces of a puzzle. It has been well documented that human memory is highly unreliable, first highlighted by a study on eyewitness testimonies in the 70s. Simple changes in how a question was asked could influence the memory a witness had of an event such as a car crash. When this was brought to public attention, eyewitness testimonies alone were no longer used as evidence in court. Many people wrongly convicted on memory statements were later exonerated by DNA evidence.

Xu Liu of the RIKEN-MIT Center for Neural Circuit Genetics and one the lead authors of the study on making changes to memory, said that when mice recalled a false memory, it was indistinguishable from the real memory in the way it drove a fear response in the memory forming cells of a mouse’s brain. “In the English language there are only 26 letters, but the combinations of letters make unlimited words and sentences, this is also true for memories,” Dr Liu told BBC News.

“There are so many brain cells and for each individual memory, different combinations of small populations of cells are activated.”

These differing combinations of cells could partly explain why memories are not static like a photograph, but constantly evolving, he  added.


Memory implantation is a technique used in cognitive psychology to investigate human memory. The high rate of people “remembering” false events shows that memories cannot always be taken at face value. Image: Digital installation ‘Annunciation’ by Artist Tom Estes. The title of the work is a Biblical term which means the announcing of ‘the incarnation’ or a materialization of the unrealized in a concrete form. The work therefore relates to multiple worlds; possible, fictional or desired worlds which though different from the one we live in, directly influences our own.

Silencing fear

Neil Burgess from University College London, who was not involved with the work, told BBC News the study was an “impressive example” of creating a fearful response in an environment where nothing fearful happened.

“One day this type of knowledge may help scientists to understand how to remove or reduce the fearful associations experienced by people with conditions like post traumatic stress disorder.”

But he added that it’s only an advance in “basic neuroscience” and that these methods could not be directly applied to humans for many years.

“But basic science always helps in the end, and it may be possible, one day, to use similar techniques to silence neurons causing the association to fear.”

‘Diseases of thought’

Mark Mayford of the Scripps Research Institute in San Diego, US, said: “The question is, how does the brain change with experience? That’s the heart of everything the brain does.

He explained that work like this could one day further help us to understand the structure of our thoughts and the cells involved.

“Then one can begin to look at those brain circuits, see how they change, and hopefully find the areas or mechanisms that change with learning.”

“The implications are potentially interventions for diseases of thought such as schizophrenia. You cannot approach schizophrenia unless you know how a perception is put together.”

David Anderson, a professor of biology at the California Institute of Technology, says the study makes an important contribution to neuroscientists’ fundamental understanding of the brain and also has potential implications for treating mental illness.

“This is a tour de force of modern molecular-biology-baed methods for analyzing processes, such as learning and memory, at the neural-circuitry level. It’s one of the most sophisticated studies of this type that I’ve seen,” he says.

Erasing Memories

Mice have previously been trained to believe they were somewhere else, “a bit like the feeling of deja-vu we sometimes get”, said Rosamund Langston from Dundee University.

A possibility in the future is erasing memories, she told BBC News.

“Episodic memories – such as those for traumatic experiences – are distributed in neurons throughout the brain, and in order to make memory erasure a safe and useful tool, we must understand how the different components of each memory are put together.

“You may want to erase someone’s memory for a traumatic event that happened in their home, but you certainly do not want to erase their memory for how to find their way around their home.”

“If you want to grab a specific memory you have to get down into the cell level. Every time we think we remember something, we could also be making changes to that memory – sometimes we realize sometimes we don’t,” Dr Liu explained.

“Our memory changes every single time it’s being ‘recorded’. That’s why we can incorporate new information into old memories and this is how a false memory can form without us realising it.”

Susumu Tonegawa, also from RIKEN-MIT, said his teams’ work provided the first animal model in which false and genuine memories could be investigated in the cells which store memories, called engram-bearing cells.

“Humans are highly imaginative animals. Just like our mice, an aversive or appetitive event could be associated with a past experience one may happen to have in mind at that moment, hence a false memory is formed.”


A neuralyzer is a device from the film Men in Black. It about the size of an average cigar tube that gives a bright flash which erases the memories of the past hours, days, weeks, months or years, depending on the chosen settings.

The Dangers

The ability to plant memories raises some serious moral concerns. We all have resistance mechanisms preventing us remembering unpleasant things. But they are still ours, stored and sorted in our conscious and subconsciousness and is therefore a part of who and what we are. They are part of our survival equipment so we do not make the same mistakes over again. When this memory is taken out of its locked drawer and is completely reformatted, without our consent, this is nothing short of Hackery. A psychological burglary which potentially can create a chaos in the whole cognitive and subconscious system.

In 1986 Nadean Cool, a nurse’s aide in Wisconsin, sought therapy from a psychiatrist to help her cope with her reaction to a traumatic event experienced by her daughter. During therapy, the psychiatrist used hypnosis and other suggestive techniques to dig out buried memories of abuse that Cool herself had allegedly experienced. In the process, Cool became convinced that she had repressed memories of having been in a satanic cult, of eating babies, of being raped, of having sex with animals and of being forced to watch the murder of her eight-year-old friend. She came to believe that she had more than 120 personalities-children, adults, angels and even a duck-all because, Cool was told, she had experienced severe childhood sexual and physical abuse. The psychiatrist also performed exorcisms on her, one of which lasted for five hours and included the sprinkling of holy water and screams for Satan to leave Cool’s body.

When Cool finally realized that false memories had been planted, she sued the psychiatrist for malpractice. In March 1997, after five weeks of trial, her case was settled out of court for $2.4 million. Nadean Cool is not the only patient to develop false memories as a result of questionable therapy. In Missouri in 1992 a church counselor helped Beth Rutherford to remember during therapy that her father, a clergyman, had regularly raped her between the ages of seven and 14 and that her mother sometimes helped him by holding her down. Under her therapist’s guidance, Rutherford developed memories of her father twice impregnating her and forcing her to abort the fetus herself with a coat hanger.The father had to resign from his post as a clergyman when the allegations were made public. Later medical examination of the daughter revealed, however, that she was still a virgin at age 22 and had never been pregnant. The daughter sued the therapist and received a $1-million settlement in 1996.

About a year earlier two juries returned verdicts against a Minnesota psychiatrist accused of planting false memories by former patients Vynnette Hamanne and Elizabeth Carlson, who under hypnosis and sodium amytal, and after being fed misinformation about the workings of memory, had come to remember horrific abuse by family members. The juries awarded Hammane $2.67 million and Carlson $2.5 million for their ordeals.

In all four cases, the women developed memories about childhood abuse in therapy and then later denied their authenticity. How can we determine if memories of childhood abuse are true or false? Without corroboration, it is very difficult to differentiate between false memories and true ones. Also, in these cases, some memories were contrary to physical evidence, such as explicit and detailed recollections of rape and abortion when medical examination confirmed virginity. How is it possible for people to acquire elaborate and confident false memories? A growing number of investigations demonstrate that under the right circumstances false memories can be instilled rather easily in some people.

Research into memory distortion by Elizabeth F. Loftus at Washington University goes back to the early 1970s, when she began studies of the “misinformation effect.” (Scientific American September 1997, vol 277 #3 pages 70-75). Elizabeth F. Loftus is professor of psychology and adjunct professor of law at the University of Washington. She received her Ph.D. in psychology from Stanford University in 1970. Her research has focused on human memory, eyewitness testimony and courtroom procedure. Loftus has published 18 books and more than 250 scientific articles and has served as an expert witness or consultant in hundreds of trials, including the McMartin preschool molestation case. Her book Eyewitness Testimony won a National Media Award from the American Psychological Foundation. She has received honorary doctorates from Miami University, Leiden University and John Jay College of Criminal Justice. Loftus was recently elected president of the American Psychological Society.

Her studies show that when people who witness an event are later exposed to new and misleading information about it, their recollections often become distorted. In one example, participants viewed a simulated automobile accident at an intersection with a stop sign. After the viewing, half the participants received a suggestion that the traffic sign was a yield sign. When asked later what traffic sign they remembered seeing at the intersection, those who had been given the suggestion tended to claim that they had seen a yield sign. Those who had not received the phony information were much more accurate in their recollection of the traffic sign.

Loftus has now conducted more than 200 experiments involving over 20,000 individuals that document how exposure to misinformation induces memory distortion. In these studies, people “recalled” a conspicuous barn in a bucolic scene that contained no buildings at all, broken glass and tape recorders that were not in the scenes they viewed, a white instead of a blue vehicle in a crime scene, and Minnie Mouse when they actually saw Mickey Mouse. Taken together, these studies show that misinformation can change an individual’s recollection in predictable and sometimes very powerful ways.


A neuralyzer, sometimes spelled as neuralizer, is a device seen in the Men in Black franchise. It is one of the signature tools and considered standard issue

Misinformation has the potential for invading our memories when we talk to other people, when we are suggestively interrogated or when we read or view media coverage about some event that we may have experienced ourselves. After more than two decades of exploring the power of misinformation, researchers have learned a great deal about the conditions that make people susceptible to memory modification. Memories are more easily modified, for instance, when the passage of time allows the original memory to fade.

It is one thing to change a detail or two in an otherwise intact memory but quite another to plant a false memory of an event that never happened. To study false memory, Loftus first had to find a way to plant a pseudomemory that would not cause our subjects undue emotional stress, either in the process of creating the false memory or when we revealed that they had been intentionally deceived. Yet she wanted to try to plant a memory that would be at least mildly traumatic, had the experience actually happened.

Loftus and her research associate, Jacqueline E. Pickrell, settled on trying to plant a specific memory of being lost in a shopping mall or large department store at about the age of five. They asked their subjects, 24 individuals ranging in age from 18 to 53, to try to remember childhood events that had been recounted to the pair by a parent, an older sibling or another close relative. Loftus and Pickrell prepared a booklet for each participant containing one-paragraph stories about three events that had actually happened to him or her and one that had not. She constructed the false event using information about a plausible shopping trip provided by a relative, who also verified that the participant had not in fact been lost at about the age of five. The lost-in-the-mall scenario included the following elements: lost for an extended period, crying, aid and comfort by an elderly woman and, finally, reunion with the family.

After reading each story in the booklet, the participants wrote what they remembered about the event. If they did not remember it, they were instructed to write, “I do not remember this.” In two follow-up interviews, participants were told there was interest in examining how much detail they could remember and how their memories compared with those of their relative. The event paragraphs were not read to them verbatim, but rather parts were provided as retrieval cues. The participants recalled something about 49 of the 72 true events (68 percent) immediately after the initial reading of the booklet and also in each of the two follow-up interviews. After reading the booklet, seven of the 24 participants (29 percent) remembered either partially or fully the false event constructed for them, and in the two follow-up interviews six participants (25 percent) continued to claim that they remembered the fictitious event. Statistically, there were some differences between the true memories and the false ones: participants used more words to describe the true memories, and they rated the true memories as being somewhat more clear. But if an onlooker were to observe many of the participants describing an event, it would be difficult indeed to tell whether the account was of a true or a false memory. Of course, being lost, however frightening, is not the same as being abused. But the lost-in-the-mall study is not about real experiences of being lost; it is about planting false memories of being lost. The paradigm shows a way of instilling false memories and takes a step toward allowing an understanding of how this might happen in real-world settings. Moreover, the study provides evidence that people can be led to remember their past in different ways, and they can even be coaxed into “remembering” entire events that never happened. Studies in other laboratories using a similar experimental procedure have produced similar results such as those conducted by, Ira Hyman, Troy H. Husband and F. James Billing of Western Washington University.


Total Recall is an action thriller about reality and memory, inspired anew by the famous short story “We Can Remember It For You Wholesale” by Philip K. Dick. Image: Douglas Quaid (Arnold Schwarzenegger) is a construction worker dissatisfied with his place in life. On the way to work he sees an advertisement on the subway for ReKall, Inc., a facility that implants fake memories of ideal vacations (1990).

In the lost-in-the-mall study, implantation of false memory occurred when another person, usually a family member, claimed that the incident happened. Corroboration of an event by another person can be a powerful technique for instilling a false memory. In fact, merely claiming to have seen a person do something can lead that person to make a false confession of wrongdoing.

This effect was demonstrated in a study by Saul M. Kassin and his colleagues at Williams College, who investigated the reactions of individuals falsely accused of damaging a computer by pressing the wrong key. The innocent participants initially denied the charge, but when a confederate said that she had seen them perform the action, many participants signed a confession, internalized guilt for the act and went on to confabulate details that were consistent with that belief. These findings show that false incriminating evidence can induce people to accept guilt for a crime they did not commit and even to develop memories to support their guilty feelings.

Research is beginning to give us an understanding of how false memories of complete, emotional and self-participatory experiences are created in adults. First, there are social demands on individuals to remember; for instance, researchers exert some pressure on participants in a study to come up with memories. Second, memory construction by imagining events can be explicitly encouraged when people are having trouble remembering. And, finally, individuals can be encouraged not to think about whether their constructions are real or not. Creation of false memories is most likely to occur when these external factors are present, whether in an experimental setting, in a therapeutic setting or during everyday activities.

The precise mechanisms by which such false memories are constructed await further research. There is still much to learn about the degree of confidence and the characteristics of false memories, and what types of individuals are particularly susceptible to these forms of suggestion and who is resistant. In 1998 Herrmann and Yoder published an article arguing for the cessation of memory implantation research with children. The criticisms referred to several studies investigating the suggestibility of children written by Ceci and colleagues. Herrmann and Yoer argue that the methods used can have negative implications for the children used such as lessen their respect for authority, be damaging for their concept of self (feel incompetent when it is pointed out that their memories are wrong) and cause stress. Ornstein and Gordon replied to Herrmann and Yoder’s article saying that although people conducting research with children have an ethical responsibility there is much to be gained from memory implantation research and “the benefits outweigh the potential risk for children involved”. Which of course doesn’t sound very ethical at all.

The Final Cut (2006) is set in a world with memory implants, Robin Williams plays a cutter, someone with the power of final edit over people’s recorded histories. His latest assignment is one that puts him in danger.

The research was funded by the RIKEN Brain Science Institute, Howard Hughes Medical Institute, and the JPB Foundation.



About Art Selectronic

Art Selectronic is an artist an artist-led initiative, that supports grass-roots contemporary art that remains unswayed by fashion, trends or the whims of government funding. The project involves ongoing research into the placing of contemporary art, it’s audiences and it’s relationship to the everyday. We place great emphasis on context. Our mission is to support new works of contemporary art and foster an audience from a wide range of backgrounds.
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