Eternal Sunshine of the Fearless Mind: Erasing Memories of Fear

Fagjun | Published 2017-08-25 10:11

Not all of our memories are pleasant.



Erasing memories of fear may soon be possible. Researchers have found a way to use pulses of light in order to remove fearful memories from the minds of mice. If scientists find a way to do the same thing for humans, it may be able to help people who are struggling with PTSD or addiction.


The premise of the study is that certain sounds can trigger memories of fear. This leads to a new way to approach dealing with fear that doesn't entail removing the ability to feel fear entirely. The researchers stressed that it's important that they selectively remove fearful memories instead. After all, the ability to feel afraid is vital to the survival of humans, as well as many other species.


However, some of the things we fear can be harmful to us instead of helpful to our survival. Thus, it can be beneficial if we no longer have a fearful response to certain stimuli.


The Science of Erasing Memories

These new findings show how mice can become fearless.



Researchers ran an experiment in which they played a high-pitched sound and a low-pitched sound for genetically modified mice. When researchers played the high-pitched sound, they accompanied it with a “mild” electric shock to the mice's feet. As expected, the mice eventually learned to associate the high-pitched sound with the electric shock, and thus began to exhibit fear whenever they heard the sound. The mice showed fear even when the researchers played the sound without the shock.


The training caused the connections between certain synapses to grow stronger. These synapses are the ones that send the high-pitched sound to the amygdala, which is involved in memories, emotional reactions, and decision-making.


Thus, the researchers targeted the signals the synapses were sending in order to erase fearful memories. They used a technique called optogenetics, which turned out to be effective in actually erasing memories associated with fear. The light pulses weakened the signals until their effects were all but gone. Eventually, the mice no longer froze in fear whenever they heard the high-pitched sound.


Optogenetics entailed using a virus to transfer genes into specific neurons involved in the pathways of the high-pitched sound. The genes then facilitated the production of proteins that respond to light.


In the Future

Is it possible to make the same experiment possible for humans?



Researchers claim that the removal of fearful memories is permanent. The mice don't relapse to a state of fear whenever they hear the high-pitched sound, showing that the fearful memory does indeed get removed.


Fear can be a healthy reaction to the world around us. It can tell us what to avoid in order to protect ourselves from harm. However, fear can become unhealthy, especially when it becomes more harmful than beneficial. Of course, this research does have its drawbacks. Its critics say that it may be too early to say that this technique can help patients with PTSD or other similar disorders. Also, it may be unethical to use optogenetics on humans.


In any case, the study is a step forward. Erasing memories may become possible in the future, though it may be different than how we think it is.

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