Modern science gives us endless possibilities to help our bodies and minds stay healthy, but some recent studies have also been the subject of controversy; for example, those related to the possibility of manipulating memories. Is this feat possible? If so, why would we want to?
Our memories are part of who we are, and the things we remember can often define our experience of the world around us. While positive memories can help us grow and thrive, negative memories do not always have such pleasant effects, but precisely these can be part of a learning curve. It is also true that there are truly traumatic memories, the recall of which can lead to serious mental health problems and disorders, such as post-traumatic stress disorder.
The study of memory ( formation, recall and forgetting ) attracts a lot of attention and curiosity among neuroscientists, psychologists and even researchers in the humanities, as there is still much that we do not understand about the processes that surround memory.
What if we could delete memories entirely?
When the brain encodes information, that data is stored in groups of neurons that form synapses, or links that allow brain cells to “communicate” with each other. Scientists often associate stronger synapses with better memory.
However, synapses can also weaken if they are not activated often enough, and the brain often loses some of these connections completely. Therefore, forgetting can occur naturally, and in fact, researchers argue that forgetting is a crucial part of learning and creating new memories.
But scientists continue to explore the many complications related to memory and recall. For example, not all of our memories are correct, and sometimes our brains “implement” forgetting as a defense mechanism.
Previous research has shown that social interactions can influence a person’s memory of an event, as well as what other people remember, or say they remember, about the same event.
For example, as some studies have shown, the memory retrieval process may mean that the original memory is rewritten, with the memory of that memory, such that the original memory is deformed.
A study published in the Journal of Neuroscience calls this “recovery-induced distortion” and explains that the distortion could occur either because the recovery process altered memory “or because it led to the formation of new associations.”
Forgetfulness as an adaptive mechanism
In addition to the questions related to how we remember the things we remember, there is also the problem of why we forget, with some researchers pointing out that forgetting sometimes occurs as an adaptive mechanism. By leaving out irrelevant details, our brains can better remember important information.
Another way that forgetting can be a helpful process is to put negative memories out of reach so that they are less distressing to the person.
Intrusive memories
But what happens when traumatic memories persist and reappear spontaneously? Experts call this the “intrusive reexperience of trauma,” and it is a fundamental feature of post-traumatic stress disorder.
And it is that memories are vulnerable during a specific time window. People who experience PTSD may spontaneously recall a traumatic memory, or feel that they are returning to the context that produced the trauma. This effect can cause the person severe distress and lead to erratic behavior.
For this reason, some scientists have wondered what approach they could take to weaken or manipulate negative memories and lessen their effect. And, we already know that it is possible to interfere with a memory and prevent it from solidifying. It is a different process from forgetting.
The drug Propranolol, for example, which doctors may prescribe for post-traumatic stress disorder, is already aimed at weakening distressing memories to lessen their effect.
However, researchers are still looking for other ways to interfere with memory. Such studies could help not only find new treatments for PTSD and other phenomena such as phobias, but could also reveal new information about how memory-related mechanisms in the brain work.
Studying memory manipulation
To try to understand whether or not we can artificially manipulate memories, a team of researchers at the Massachusetts Institute of Technology in Cambridge tried to instill false memories in mice. This initial study, which appeared in the journal Science in 2013, used an optogenetic technique to manipulate the formation of a “hybrid” memory in the brains of a group of mice . This method requires the use of beams of light to activate neurons that researchers have designed to respond to this stimulus.
The experiment was successful: the mice began to associate fear with a space in which they had never had a bad experience.
In an additional study by the same team, published in Nature in 2014, the researchers were able to use the same technique to “turn off” negative associations in the brains of mice.
But are such animal studies really indicative of what would happen in the human brain under similar circumstances?
Experts say the similarities are strong enough to give us a pretty good idea of how the human brain would function in the same context. And, in essence, we are not as different from non-human mammals as mice and rats.
Reference: Bidirectional switch of the valence associated with a hippocampal contextual memory engram. Roger L. Redondo Joshua Kim, Autumn L. Arons, Steve Ramirez, Xu Liu & Susumu Tonegawa. Nature volume 513, pages 426–430 (18 September 2014) DOI: https://doi.org/10.1038/nature13725
