One of the oldest ideas of psychology is that memories make the person. They’re not the easiest thing to sort out, but they’re just as definitive of who you are as your hair color — or even the hat or shirt you’ve picked out as a particular favorite. Whether they’re pleasant — imagining waking early on a Christmas morning of your youth — or painful — the last thing you see before receiving bad news, going through a difficult breakup, and regularly being reminded of your ex, they consistently shape your experience for the rest of your life, for better or worse.
We may, however, be not all that far from a time when we could restart the clock completely — eliminating those painful memories and making way for more pleasant ones — allowing us to start over each time without having to live in the past. In the most extreme cases of being burdened with unwanted and painful memories, the individual suffers from post-traumatic stress disorder (PTSD), in which the brain feels as if it is constantly under a state of attack, and they have difficulty managing harmless tasks of their day to day lives. Something like thunder could produce a neural response similar to a traumatic episode they had and causes them to relive that particular moment in time.
It seems like a fantasy concept, but the technology to make it possible isn’t all that far away. Right now, computational neuroscientists are working in the proof-of-concept stages for a therapeutic treatment known as “decoded neurofeedback” (DecNef) in which the brain accumulates and processes neural signals and can modify select ones using computer algorithms.
What Is Decoded Neurofeedback?
We tend to think of the brain as rather passive — a gelatin that sits back in our skulls and takes in the information of the world around us the way we take in our favorite show from the sofa, but it’s actually a massive powerhouse sending off electrical signals to initiate our every movement, or responding to every stimulus we encounter, including those we don’t fully appreciate. Dr. Aurelio Cortese is a computational neuroscientist and the principal investigator at ATR Computational Neuroscience Labs, who uses these signals to set up the intricate process that is DecNef.
“In DecNef we use neuroimaging data,” Cortese says, “a big magnet that scans our brain — and measures changes in the levels of oxygen in the cerebral blood. This data is then processed in real-time through a local computer, that selects the data from the relevant brain area.”
Cortese has contributed data collection to many of the studies conducted on DecNef, and he put together a new data set review published in the journal Scientific Data.
The big magnet in question belongs to a functional MRI machine, the large tunnel-like machine similar to a hospital CT scan device that is used to examine individual brains in neuroscience experiments. Gathering fMRI data is typically a drawn-out routine procedure, but what’s different about DecNef, according to Cortese, is that it uses the process of machine learning in order to extract certain patterns of neural activity and then retarget them.
“Machine learning is used to learn the neural representation of the target mental representation in the first place,” Cortese explains. “This machine learning decoder is then used in the neurofeedback procedure, to detect the activation patterns and compute the likelihood that it corresponds to a target pattern.”
The DecNef participants were given a small reward whenever the machine found a target activation pattern initiated in their brain. “It aims to give participants control over some specific brain processes.”
How Does It Work?
The researchers gather their fMRI data after their test subjects are either exposed to painful stimulus, such as mild electric shock, but sometimes a more psychological fear-stimulus, like having to look at pictures of an assailant. A machine-learning algorithm then analyzes the data picture from each patient to discern patterns in their brain activity.
In another session, the participants then play a game for a small cash reward where they link visual targets to their brain activity. They think they’re playing a video game, but they are actually linking their current neural activity with a snapshot of their neural activity (each one reduced to a series of dotted squares) when they were exposed to painful stimuli, through a series of trial and error.
There have been a number of research studies in recent years that have used this method and found it could reduce fear associated with painful memories in noticeable ways, even when it came to patients suffering from PTSD, but they are still not entirely sure of the reason why this is the case.
The top competing theories are a possibility that DecNef acts in a way that is analogous to exposure-based therapy (decreasing the state of fear in a PTSD patient gradually through slight degrees of exposure) or counterconditioning (in which the patient learns to substitute fear from one stimulus with a positive reaction — rather than waiting for an attack, they think of something else to anticipate, such as a reward.
This doesn’t guarantee that an individual’s memory will be deleted, but rather, it will lose its potency, and the individual will no longer fear having to relive it again.
“One of the main goals is to reduce the impact of traumatic memories, or of phobic items,” said Cortese. “By repeatedly pairing the neural occurrence of the memory or the object with a small reward, the brain can unlearn the fearful aspect.”
Is This What We Want To Happen?
Aside from just treatment for PTSD, DecNef could have a number of smaller but practical applications as well. Cortese identified ways in which this practice could also serve to train attention, increase our memory function, and reduce physical pain.
Virtual reality is another popular alternative to the traditional approaches to PTSD treatment, but even when it comes to virtual reality, patients are still inevitably exposed to fear stimulus similar to the triggers that produced their symptoms. For some of the more extreme cases, exposure-based therapy isn’t always effective.
With DecNef techniques, the patient could have their memories modified without needing to revisit the same experience that made their memory so painful to begin with. The proof-of-concept trials taking place today for DecNef usually require the researchers to capture the brain’s response to negative stimulus while the patient is in the lab, but there is research, published in the Proceedings of the National Academy of Sciences, suggesting that it could soon be possible to develop and use a surrogate group of neural signals for the therapy instead. That means that patients with severe cases might not have to face any kind of re-exposure at all.
“This is already quite an achievement since it means we could build the machine learning decoders without ever having to present the traumatic image to know what is the mental representation for that person,” said Cortese.
Should We Erase What Was?
Memories are a definitive part of who we are — so whether they be painful or sad, we invariably feel a great deal of ownership over them. This is a significant reason why what is one of DecNef’s best attributes — its ability to modify bad memories — may also be the reason it is highly controversial.
“Because DecNef can be used to partly change mental representations without the person being entirely aware of it, it should be used only in very specific settings, with proper oversight from ethic boards,” said Cortese.
Kellmeyer believes the technology could also raise a number of unprecedented ethical concerns — making it potentially easier to hack data and even one’s own thoughts. While reporting and replacing a stolen credit card is fairly easy to do, experiences can’t be renewed or reissued so easily.
“Therefore, these concerns need to be addressed both at the level of careful ethical analysis but also through regulations and laws that prohibit such manipulative uses of memory-modification.”
Cortese is hoping for these ethical concerns to be sufficiently dealt with, so researchers are able to use the therapy as intended, loosening the burden of dark memories on their patients.
“The hope is that it will one day be possible within a few sessions paired with medical/psychological counseling to remove a traumatic memory, or to reduce depression symptoms, or improve other psychiatric mental states,” said Cortese.
“With a little further development and fine-tuning, this technology really has the potential to provide help to individuals facing disorders of the mind.”
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