Despite how easy movies like Eternal Sunshine of the Spotless Mind, Men in Black, and Total Recall make it seem, memory manipulation or erasure in humans is still a distant dream in the real world–and for good reason. While many researchers agree it could revolutionize things like PTSD and other mental health treatment–not to mention delete memories of embarrassing and cringe moments in our lives–they are wary of tampering too much. Even our worst memories have important functions.
“Our memories are what make us who we are,” Sheena Josselyn, a memory and learning researcher at the Josselyn Frankland Lab at the Hospital for Sick Children in Toronto, Canada, told The Daily Beast. “And when we start messing with them, without there being a real imperative to do so, I think that we can really mess things up at the societal level. So I think it’s really important that we do these sorts of interventions very sparingly.”
Although we understand very little about how the brain works, research undertaken in the last decade is slowly illuminating the path to understanding how memories form, and how they are stored and retrieved. Studies show it is possible to erase specific memories, create false memories, or reduce the trauma and recall associated with a distressing memory–at least in snails and rodents. These findings, while not yet able to be used in humans for memory manipulation, have laid the groundwork for future manipulation.
In 2014, MIT researchers Steve Ramirez and Xu Liu, were able to manipulate a mouse into thinking it had received a shock inside a triangular metal box–effectively inserting an entirely false memory into the mouse’s brain. The researchers put the mice (which had been genetically engineered to render the target area in their brains sensitive to light) in a triangular box, which activated specific neurons in their brains.
They then put the mice in a square box, and administered a foot shock while shining a laser on the neurons associated with the triangular box. This was done by first surgically implanting thin laser filaments into the mice’s brains and then activating the laser at the exact moment the shock was administered.
The mice immediately started to display fearful behavior in the triangular box–indicating that they remembered experiencing a shock in it, even though that had never happened. Ramirez and Liu’s findings opened the door to newer research and breakthroughs in memory implantation and erasure.
More recently, in 2017, researchers at Columbia University Irving Medical Center and McGill University were able to show that it may be possible to effectively eliminate the triggers that bring on distressing recall of a traumatic memory, in some cases. Samuel Schacher, co-author of the study, explained in an interview with Columbia University that a victim who had been mugged in a dark alley would rightly be scared of dark alleys after the incident. They may also experience fear or distress when seeing something in the area during the assault, such as a mailbox.
The fear induced by the sight of the mailbox is called a non-associative memory. These non-associative memory can cause trauma-associated disorders like PTSD to relive the distress and fear they experienced during the traumatic event when they encounter sights, sounds or smells that are associated with it. This obviously impacts their quality of life, and is what memory researchers are trying to find a solution to.
Part of the reason is due to the fact that traumatic memories tend to take hold of the brain much more firmly than non-distressing memories. “A critical function of the nervous system is to remember experiences, especially when they are relevant to one’s survival or reproduction,” Schacher, co-author of the Columbia University study, and former professor of neuroscience in the Department of Psychiatry at CUIMC, told The Daily Beast. So threatening events, in particular, are stored in the brain for longer.”
He added, “At one point in your life, you may have realized that if you touch fire, you will burn yourself, and it is permanently stored in your brain.”
Schacher’s research seeks to reduce the emotional impact of a traumatic memory while keeping the actual memory of the trauma intact. In a study he co-authored published in the journal Current Biology in 2017, his team was able to selectively erase different memories stored in the same neuron in snails.
Similarly, Richard Huganir, director of the department of neuroscience at the Johns Hopkins University School of Medicine, was able to show in 2010, that it was possible to reduce the fear associated with a traumatic memory in mice, by removing certain proteins (calcium-permeable AMPARs) from the region of the brain encoding emotional memory.
However, no existing drugs are able to remove these proteins in such a targeted manner in humans. If there was a way of doing this, then it would be better than exposure therapy, which involves facing traumatic thoughts, memories or associations with the help of a therapist. This method is prone to relapse. Huganir explained to The Daily Beast that “because it would erase the emotional contents of the memory [patients] wouldn’t have relapses.”
Along similar lines, Josselyn’s lab in Toronto studies how the brain encodes memory. They have successfully shown how it may be possible to erase fearful memories from the brains of mice, by killing a certain population of brain cells in a targeted way.
“We found cells that we thought were really important in a memory, and we killed this very small population of cells in a really targeted way in mice,” Josselyn told The Daily Beast. “And we found that the memory was essentially erased.”
Months or years after having suffered a traumatic experience, the memory of the trauma can continue to debilitate a person– often manifesting as PTSD. The disorder is characterized by episodes that bring back the suffering and distress of the original trauma, often triggered by the sight, sound, or something else associated with the trauma. This can be a series of nightmares, flashbacks or anxiety attacks.
Erasing the association between a “trigger” and the trauma, or reducing the emotional impact of traumatic memories could offer people who live with the most severe forms of PTSD, or other trauma-induced disorders, some relief. This can reduce the anxiety associated with memory deletion if done in a way that targets the emotional impact while maintaining the original memory.
“In the case of someone suffering from [PTSD], you don’t want to erase the fact that they underwent some trauma,” Schacher said. “You don’t want to erase the memory itself.”
For instance, someone who has been abused may find themselves triggered by loud voices, or a perfume similar to something their abuser wore. Schacher’s work suggests that there may be a way to break the link between triggering factors (such as loud voices or perfume) and the trauma. The association between loud voices, perfumes or other triggers and trauma can be removed while the memory is kept intact. This will prevent flashbacks.
Discovering a way to erase memories isn’t the only way this research could illuminate the way forward. It may also be possible to help those with the opposite type of memory disorder, such as Alzheimer’s or dementia.
“I think there’s two sides of the coin: too much memory or not enough memory,” Josselyn said. She pointed out that in the early stages of diseases like Alzheimer’s “there are memories, but people can’t seem to find them.”
“So if we understand a little bit more about how memories are made, and how to retrieve them, maybe we can help unlock some of these forgotten memories in people with dementia,” she added.
Although memory manipulation is still far from being reality, ethical and medical concerns abound.
Would we even be ourselves, with enhanced or suppressed memories? It’s possible that it can cause problems like dissociative identities disorder, a reaction to trauma that makes patients dissociate from their trauma and close off. Or cause anxiety or panic attacks for people whose traumatic memories are suppressed.
There are also concerns about what might happen if this sort of technology fell into the wrong hands. What could a military or government organization do with the power to enhance or erase memories? The idea of an organization like Men in Black erasing memories in order to maintain secrecy is not so farfetched anymore.
Moreover, there could also be issues surrounding disparity: Who exactly gets to enhance or erase their memories and who doesn’t? It’s not fair to limit it only to wealthy people. There may very well one day be a class system partially based on access to memory technology.
“If we do get general cognitive enhancers that everybody can take, there isn’t going to be equal access to those drugs,” Huganir said. “They’re gonna cost money and so of course they won’t be very equitable. They won’t be available to everybody and there’s also potential for abuse as well.”
Although understanding how memories work is critical to treating memory disorders or ease trauma, researchers agree that these treatments must be reserved for those suffering from severe trauma, PTSD, or other memory issues.
Tempting as it may be to rid ourselves of the memory of an embarrassing drunk karaoke performance, or rid our minds of memories of our exes, using memory manipulation in those ways could be incredibly damaging otherwise. And science is still a long way off from being able to do this accurately or safety.
“I think this type of treatment would only be for incredibly invasive, troubling memories–not just sort of our everyday ‘Yikes, that was horrible!’ sort of memory,” Josselyn said.
Although we’re still a long way off from being able to press a button (or more realistically, administer a drug) and reliably wipe a specific memory from a person’s brain, every new finding takes us a step further, shedding light on how memory functions, how it malfunctions, and what to do when that happens.
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