Scientists Make Mice “Remember” Things
That Didn’t Happen
Researchers manipulate mouse neurons to create a false memory; the work could lead to a better understanding of how memories form.
- By Susan Young on July 25, 2013
http://www.technologyreview.com/news/517226/scientists-make-mice-remember-things-that-didnt-happen/
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Scientists have created a false memory in mice by manipulating neurons that bear the memory of a place. The work further demonstrates just how unreliable memory can be. It also lays new ground for understanding the cell behavior and circuitry that controls memory, and could one day help researchers discover new ways to treat mental illnesses influenced by memory.
In the study, published in Science on Thursday, the MIT scientists show that they can modify a memory and have a mouse believe it experienced something it didn’t. Susumu Tonegawa, a neuroscientist at MIT, and members of his lab used mice that were genetically modified to allow for certain neurons to be activated with a flash of light; the technique enabled the researchers to activate a memory that caused a mouse to believe it had experienced electrical shocks in a particular box, even though no such thing had happened there. “The process of memory is nothing like a tape recording,” says study co-first author Steve Ramirez. “It’s really malleable and susceptible to the incorporation of new information.”
The results are “really mind-blowing,” says Sheena Josselyn, a neuroscientist at the Hospital for Sick Children in Toronto. “It shows that your memories are really just activities of different cells, and they can take the place of an actual thing that happened by just activating some cells in the brain,” she says. “People have been playing around with this idea for a while, but having a theory and showing it are two different things.”
Advances in neuroscience methods and technology are giving researchers an unprecedented understanding of the biological basis of memories. In recent years, researchers have uncovered details about the molecular and cellular components of memory creation and the electrical language that cells use to recall memories (see “Making Memories” and “A First Step Toward a Prosthesis for Memory”).
More broadly, neuroscientists are increasingly exploring human cognition at its molecular and cellular origins. Someday, this deeper understanding could lead to better or novel treatments, such as memory implants that replace lost memories (see “Memory Implants”) or novel drugs to boost beneficial memory reconsolidation.
Previously, the MIT-based team had shown that it could pinpoint the location and assemblage of cells that carry a memory, and that activating those cells stimulated memory recall in mice. To create the new, false memory, Tonegawa’s team reactivated a mouse’s memory of a safe place while the animal received shocks in its feet, thus transforming the original memory.
First, the team used genetic tricks to label the brain cells involved in the memory of a chamber that was safe and neutral. The next day, they put the animal in a second chamber, a completely different setting. There, the animal got foot shocks while the researchers simultaneously shone light to reactivate the memory of the harmless first chamber. When the animal was put back in the first chamber, it fearfully froze—a clear indication that it remembered getting shocked in that chamber, even though that never happened. “It formed a false memory,” says Ramirez.
One of the long-term goals for the work is to be able to identify new methods for helping patients with cognitive disorders. “It’s not because we want to implant or ‘incept’ some false experience into the human mind, but because it could be useful, eventually, to develop methods to reduce cognitive abnormalities associated with psychiatric diseases, such as the delusions experienced by patients with schizophrenia,” says Tonegawa.
The work also explores…..(Continues)
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