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Scientists Plant False Memories in Mice

FMSF News Alert - July 29, 2013

Ramirez, S., Liu, X., Lin, P., Suh, J., Pignatelli, M., Redondo, R.L., Ryan, T.J., Tonegawa, S. (2013, July 26). Creating a false memory in the hippocampus. Science, Vol. 341 No. 6144, pp. 387-391.

The web has been abuzz with articles about an experiment by a group at MIT who implanted false memories in mice. It’s true. They did. And the story is fascinating at many levels.

Where it happened.

Graduate student Steve Ramirez and five colleagues worked in the MIT center/lab of Susumu Tonegawa. Tonegawa received a Nobel Prize in Physiology in 1987 for discovering the genetic mechanism that produces antibody diversity. A molecular biologist, he then turned his attention to the molecular and cellular basis of memory formation. Highly talented researchers in a highly respected lab have spent years and years studying this subject.

What Happened?

Ramirez and colleagues put mice in a chamber that had glowing reddish light. The mice were allowed to explore and do what mice like to do. Happy mice.

The next day the mice were put into another chamber. The unsuspecting mice were given electric shocks to their feet at the same time, as researchers were able to shine light in their brains using a new "optogenetic" technique. The mice were not happy. They were terrified. This is called "fear conditioning."

On a third day, the mice were placed again in the first chamber where they had been happy. But they were now terrified. They expected to receive shocks. They had a false memory that this was where they had been hurt because of the association with the light.

What is optogenetics?

In order to study false memories, the researchers needed to identify the brain regions that are involved in producing internal mental representations. Then they needed to disturb the activity. They wondered if the internal representations could be affected by external stimuli to create new memories.

Steve Ramirez and colleagues used a new technique called optogenetics to study memory in mice brains. Optogenetics is a huge breakthrough, a thrilling new research tool. It uses light-sensitive proteins to manipulate RNA instructions with the cell. With it, scientists can activate or suppress specific naturally occurring genes instantly. They don’t have to engineer genes. What does all that mean?

A video from MIT explaining the technique in a relatively clear way is totally fascinating. You can watch it several times and each time pick up a bit more information about the technique. I highly recommend:

Do false memories in mice have anything to do with FMS?

At the level of activity being tested, there is not much difference between mouse and human brain. In both, memories form in an area of the hippocampus. This is the closest researchers have ever been to finding a location in the brain and saying that it is a memory. This is a huge result. The results are "really mind-blowing." [1]

Daniel Schacter, memory researcher and psychology professor at Harvard said: "Although it is not clear how the false fear memory established in mice is related to false memory phenomena in humans, the possibility of having an animal model for exploring a particular kind of false memory associated with the hippocampus is exciting." [2]

Humans are imaginative and they constantly have internal brain activity. It is entirely possible that people associate what is happening in our minds with good or bad notable ongoing events. According to study author Susumu Tonagawa: "In other words, there could be a false association of what you have in your mind rather than what is happening to you." Tonagawa also said that by showing how false memory and genuine memory are based on almost identical brain mechanisms, the study might help prevent future cases of wrongful conviction. "We hope our future findings along this line will further alert legislatures and legal experts how unreliable memory can be." [3]

1. Young, S. (2013, July 26). Scientists make mice "remember" things that didn’t happen. MIT Technology Review. Retrieved on July 26, 2013 from

2. Johnson, C. (July 25, 2013). MIT scientists plant false memory in mouse’s mind. Boston Globe. Retrieved on July 26, 2013 from Boston Globe

3. Fields, L. (2013, July 26). Scientists implant false memories in mouse’s brain. Retrieved on July 26 from

4. Gorman, J. (2013, July 26) Scientists trace memories of things that never happened. New York Times A3.