Memory erasure

Memory erasure has been shown to be possible in some experimental conditions; some of the techniques currently being investigated are: drug-induced amnesia, selective memory suppression, destruction of neurons, interruption of memory, reconsolidation,[1] and the disruption of specific molecular mechanisms.[2]

There are many reasons that research is being done on the selective removal of memories. Potential patients for this research include patients with psychiatric disorders such as post traumatic stress disorder, or substance use disorder, among others.[2]

Memory erasure is also featured in numerous works of fiction, with fictional methods and properties that do not necessarily correspond with scientific reality.

Research focused on gaining a better understanding of what memories are has been going on for many years, in this way so has research in memory erasure. The basis for the recent history for memory erasure has been focused on determining how the brain actively keeps memories stored and retrieves them. There have been several instances where researchers found drugs that when applied to certain areas of the brain, usually the amygdala, have relative success in being able to erase some memories. As early as 2009 researchers were able to trace and destroy neurons involved in supporting the specific type of memory that they were trying to erase. This caused the erasure of the target memory.[3]

Aside from the biotechnology approach to studying memory, research in psychiatry on how memories work has also been going on for several years. There have been some studies that show that some behavioral therapy can erase bad memories.[4] There has been some evidence that psychodynamic therapy and other energy techniques[5] can help with forgetting memories among other psychiatric issues there is no proven therapeutic approach for trying to erase bad memories.[6]

There are several different types of possible patients that have the potential to draw great benefit from the selective memory erasure; these include people with drug addiction, or posttraumatic stress disorder (PTSD). PTSD patients may include war veterans, people who witnessed horrific events, victims of violent crimes and many other possibly traumatic events. These potential patients have unwanted memories that can be absolutely devastating to their daily lives and cause them to not be able to function properly.[7]

Research continues, and in 2020, researchers were looking at potential new approaches to PTSD treatment.[8][9]

There are three main types of memories: sensory memory, short-term memory, and long-term memory. Sensory memory, in short, is the ability to hold sensory information for a short period of time, for example, looking at an object and being able to remember what it looked like moments after. Short-term memory is memory that allows a person to recall a short period of time; this can be a few seconds to a minute. Short-term memory allows people to remember what happened during that short time span without actually practicing the memory. Long-term memory has a much larger capacity than the prior two and actually stores information from both these types of memories to create a long lasting and large memory. Long-term memory is the largest target for research involving selective memory erasure.

Within long-term memory there are several types of retention.[10] Implicit memory (or ‘muscle memory’) is generally described as the ability to remember how to use objects or specific movements of the body (e.g. using a hammer). Explicit memory, (or ‘declarative memory’) is that which can be consciously drawn upon by a person to remember.

Explicit memory can be split into further subcategories; episodic memory, which is the memory of specific events and the information surrounding it, and semantic memory, which is the ability to remember factual information (e.g. what numbers mean).[11]

A type of memory of main concern for memory erasure are emotional memories. These memories often involve several different aspects of information in them that can come from a variety of the different categories of memories mentioned above. These emotional memories are powerful memories that can illicit strong physiological effects on a person.[12] An example of an emotional memory can be found in patients with PTSD, for these patients a traumatic event has left a lasting emotional memory that can have powerful effects on a person even without them consciously retrieving the memory.[13]

A way of selectively erasing memories may be possible through a modified Gamma Knife machine that ionized neurons at nanometer cubic scales in a gene-therapy-approach mouse experiment at Stanford. In 2017, researchers at Stanford demonstrated a technique for observing hundreds of neurons firing in the brain of a live mouse, in real time, and have linked that activity to long-term information storage.[26][27][28]

The Stanford researchers first used a gene therapy approach to cause the mouse's neurons to express a green fluorescent protein that was engineered to be sensitive to the presence of calcium ions. When a neuron fires, the cell naturally floods with calcium ions. Calcium stimulates the protein, causing the entire cell to fluoresce bright green. A tiny microscope implanted just above the mouse's hippocampus, a part of the brain that is critical for spatial and episodic memory, captures the light of roughly 700 neurons. The microscope is connected to a camera chip, which sends a digital version of the image to a computer screen. The computer then displays near real-time video of the mouse's brain activity as a mouse runs around a small enclosure, which the researchers call an arena. The neuronal firings look like tiny green fireworks, randomly bursting against a black background, but the scientists have deciphered clear patterns in the chaos. "We can literally figure out where the mouse is in the arena by looking at these lights," said Mark Schnizer, an associate professor of biology and of applied physics. When a mouse is scratching at the wall in a certain area of the arena, a specific neuron will fire and flash green. The group has found that a mouse's neurons fire in the same patterns even when a month has passed between experiments. So the idea works by first deducing what neurons firing bright green hold which specific task the mouse was doing, then ionizing less than 1% of the neurons firing bright green, then check to see what the mouse remembers after ionizing the neurons that fired bright green. Then you ionize 2% of the mouse's neurons then check to see if the mouse remembers the task. Then you ionize 3% then 4% of the neurons firing bright green, and so on up to 25% until the specific memory is erased, each time checking to see if the mouse forgets the task. The modified gamma knife research is currently being carried out at the National Institute of Health (NIH).

As with most new technologies the idea of being able to erase memories comes with many ethical questions. One ethical question that arises is the idea that although there are some extremely painful memories that some people (for example PTSD patients) would like to be rid of, not all unpleasant memories are bad.[7] The ability to soften or erase memories could have drastic effects on how society functions. The ability to remember unpleasant effects from one's past has a huge impact on the future actions they may take. Remembering and learning from past mistakes is crucial in the emotional development of a person and helps to ensure they do not repeat previous errors.[29] The ability to erase memory could also have a massive impact on the law. When it comes to determining the outcome of a trial, the ability to modify memory could have a massive impact on the judicial system. Another ethical question that arises is to how the government will use this technology and what restrictions would need to be put in place. Some worry that if soldiers can go into battle knowing that the memories created during that time period can simply be erased they may not uphold military morale and standards.[7] Many are also skeptical with who should be able to have procedures done on them, so they are urging for a set of laws to determine this.

Memory erasure has also been a common topic of interest in science fiction and other fiction. Several notable comics, TV shows and movies feature mindwipes, including Telefon, Total Recall, Men in Black, Eternal Sunshine of the Spotless Mind, Black Mirror, The Bourne Identity, NBC's Heroes and Dollhouse.[30] Novels that feature memory erasure include The Invincible by Stanisław Lem, some of the Harry Potter novels (including Harry Potter and the Chamber of Secrets) by J. K. Rowling, and The Giver by Lois Lowry. Several works by Philip K. Dick are about mindwipes, including "Paycheck", "We Can Remember It for You Wholesale" (which served as the inspiration for Total Recall).