Science Models
Science Fair Projects

Erasing and Implanting Human Memory

Published on Sep 12, 2023


This project describes how to utilize the memory formation mechanism discovered in recent years together with optogenetics, a technology used to manipulate human brain cells, to cure Post-traumatic Stress Disorder (PTSD).

It has been discovered that memory is stored in brain cells called neurons that physically reside together, rather than scattered throughout the brain. Such groups of brain cells are called engrams, referring to where memory is stored. As a result, it is possible to target an engram. We can manipulate them in such a way that people can forget specific memories either temporarily or permanently. Since only specific brain cells related to specific memories are targeted, all the other memories are intact. However, that isn’t the best part. We can plant good memories into the human brain as well!

The above are achieved via optogenetics, a technology using light to control neurons, the brain cells responsible for processing and transmitting information. The process starts with identification of the neurons associated with a particular engram that is responsible for a specific piece of memory. Then, light sensitive opsins are inserted into the engram, turning the neurons in that area light sensitive. After that, fiber optics or micro LEDs are implanted to target the light sensitive neurons. The light is controlled by a microchip to turn on or off those neurons to manipulate memory.

For forgetting a specific memory, the light is activated to control the neurons that release certain chemicals, such as alpha-CaM kinase II, that erase memories. Alternatively, the light can also be used to deactivate neurons responsible for memory storage, preventing the memory from being recalled.

For implanting good memories, the process is more complicated. The subject is prepared with memories of good feelings, such as a delicious dinner being served. Later, the subject is put in another environment, such as the dirty small room where his poor family lives. The light is then turned on to recall the good feeling in this environment, effectively creating the false memory that the good feeling took place in this environment. As a result, the subject likes this environment.

After the traumatic memory is removed, and the good memory is implanted, the PTSD patients are able to escape from the previous event, and restore their life.


Fear triggers many split-second reactions in the body to prepare to defend against the incoming danger or to avoid it. This “fight-or-flight” response is a normal and healthy reaction meant to protect a person from harm. But in post-traumatic stress disorder (PTSD), this reaction has altered or damaged. People who have PTSD experience fear and stress even after the danger has passed for a very long time. It interferes with everyday life, because these people cannot stop the recollection of the horrifying memories that happened.

Most people who see traumatic events don’t develop PTSD, but nonetheless, PTSD develops after an event that involved harm or the threat of harm. The person who develops PTSD could be a victim or witness of the terrifying event, but the person will experience the event over and over. Currently, the main treatments are to visit a psychologist or counselor to help the brain “get over” the event, or to go to a psychiatrist to take some medication to help alleviate the stress. There are many other therapies such as art therapy to relieve stress indirectly.

Symptoms of PTSD may include re-living the event, avoidance of things that remind you of the traumatic event, negative changes toward beliefs and attitudes, and feeling keyed up.

Erasing and Implanting

As shown in the diagram here, many Americans have experienced trauma. About 60% of men and 50% of women experience at least one traumatic event. Of those who do, about 8% of men and 20% of women will develop PTSD. For some events, like combat and sexual assault, more people develop PTSD.

3.5% of adults in USA are estimated to be suffering from post-traumatic stress disorder (PTSD) over the course of a given year. A new effective treatment would mark a milestone for mental-health and well-being.

The Cause

Studying parts of the brain involved in dealing with fear and stress helps researchers to better understand possible causes of PTSD. One such brain structure is the amygdala, known for its role in emotion, learning, and memory. The amygdala appears to be active in fear acquisition, or learning to fear an event (such as touching a hot stove), as well as in the early stages of fear extinction, or learning not to fear. Another such brain structure is the hippocampus. The hippocampus is important for forming memories, but in people with PTSD, the hippocampus has a significantly lower volume.

Stathmin is necessary for the creation of fear memories. Some people have more stathmin in the brain than others, and thus are more prone to PTSD. GRP is another signaling chemical in the brain released during emotional events. A lack of GRP may result in less capability to cope with the traumatic event. Serotonin also plays a role in the happiness of the person. If serotonin levels are low, then the person is more likely to develop PTSD.

Storing fear extinction memories and dampening the original fear response appears to involve the prefrontal cortex area of the brain, involved in tasks such as decision-making, problem-solving, and judgment. Certain areas of the prefrontal cortex play slightly different roles.

How Memory Works

The term “engram” is used to describe where memory is stored. There are many engrams in different regions of the brain, each used for a different purpose. For instance, the amygdala is responsible for fear memories and the interpositus nucleus is responsible for conditioned stimulus.

Through experiments in mice, researchers discovered that neurons associated with memory can be boosted with a protein called CREB, and memories can be erased with a protein called alpha-CaM kinase II. Also, those neurons can be activated to form false memory.


For short term memories, a protein called Kinase A is produced. However, sometimes, Kinase A is produced in such abundance that it causes MAPK, another protein, to be produced. MAPK causes a protein called CREB to be produced. CREB is essential for forming long-term memories.


Evolution of human beings allows people to forget things because the quality of life rests with the selective erasure of memory. Recent research suggests that fear memories can be near instantly erased and that specific proteins have significant powers to abolish them. This happens through production of a protein called alpha-CaM kinase II. Scientists have found that this protein can be used for selective deletion of fear memories in mice.

False Memory

People are found to have false memory too. For example, in many court cases, defendants were found guilty based on testimony from witnesses who were sure of their recollections, but DNA evidence proved otherwise. Researchers in MIT found that by reactivating neurons associated with a particular memory, false memory could be planted into the brains of mice.

Implanting Memory

Specific memories, such as a visit to a friend, are saved in interconnected neurons called an engram. When that memory is being recalled, the engram becomes active. On the other hand, when those exact neurons are reactivated in someone else’s head, another person can experience that memory.

Also, memories are interlinked. For example, if somebody walks on a quiet street every day, that environment is stored in the person’s memory. If that person is robbed on that street one day, the terrible experience is linked to the memory of that street. Hence, the next time the person walks on the same street, that person will feel unease.

Based on the theory above, a group of neuroscientists in MIT let by Nobel Laureate Susumu Tonegawa successfully implanted false memories in mice’s brain.

Implanting Human Memory

Tonegawa and his group first put a mouse in a chamber. While the mouse is memorizing the chamber, they marked the mouse’s engram in the hippocampus with a special protein called ChR2. Now they know which neurons in the engram is involved for memorizing the chamber. Those neurons are marked in white dots as shown in the picture.

Next, they put the mouse in a second chamber that is very different from the first chamber. Simultaneously, Tonegawa and his group activated the neurons marked in the previous step with a technology called optogenetics.

We will talk about optogenetics in a separate section. This technology allows people to use light to activate specific neurons being targeted. While those neurons are activated, the mouse recalls the environment in the first chamber, even though they are physically in the second chamber. At the same time, the mouse is electrocuted. This caused a memory of fear to be stored in the mouse’s memory.

Now, the mouse is placed back into chamber 1, where they never actually experienced an electrical shock before. The mouse froze, as if it were electrocuted in Chamber 1. The false memory was successfully implanted into the mouse’s brain!


The technology proposed on this website brings health back to patients suffering from PTSD. They can now choose what memory to forget, and what memory to implant. It provides fairness to the people who were not lucky enough to experience the happy life other people did. They can have a chance to choose a better memory, and a better life. Large expenses spent on caring for and helping cure PTSD patients can be saved. Furthermore, those people are willing back to school or the workplace, allowing them to contribute to society.

However, there are always two sides to a coin, and this solution is no exception. An instantly thought of one will be the fear of mind control. This technique provides a free pass to an apocalypse where everyone’s brains are enslaved. When this technology is employed for illegal purposes, people’s memory can be wiped out for illegal motives, and fake memories leading to criminal activities can be injected.

This will also lead to a lot of debatable topics. For example, if a person has any wrongdoing based on his manipulated memory, who is to be responsible? Who is responsible to make the final decision on which part of the memory shall be erased? Who is responsible for the consequences of the new memories being implanted? If the technology is defective, creating unwanted effects on the user’s memory and causing unwanted behaviors, who takes the responsibility? Do parents have the right to decide whether their children should forget certain things, and remember certain fake memories instead?

Essentially, we have to ask ourselves a very fundamental question: do we wish for the human being’s mind to be programmable like a computer? Is it a positive or negative thing to have such technology available?


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