Blade Runner. Total Recall. Inception.
We've had some great examples of memory implantation in our science fiction over the years, but now the science is moving out of fiction and into reality after a team of researchers successfully implanted false memories in mice.
To implant the memories, the researchers something called used optogenetics — the use of optics and genetics to control individual neurons in the brain. They first genetically engineering mice so that they would have light-sensitive proteins — called Channelrhodopsin-2 or ChR2 — in their hippocampus, which is the part of the brain used in forming memories. Therefore, when the mouse formed memories, the researchers could effectively see which regions of the hippocampus were activated. Also, using light they could activate those areas to have the mouse recall those memories, and they achieved that by having a thin fibre optic cable implanted in the mouse's head.
Placing the mouse into a box — called Chamber A — they let it calmly explore for 10 minutes, forming memories about its environment, and they recorded where the memories were formed (panel 1 of the image above).
The next day, they placed the mouse into a different box — Chamber B — with a different environment, and they used light through the fibre optic cable to activate the memories it formed the day before. At that time, while the mouse was remembering Chamber A, they delivered mild shocks through the floor of the box, which caused the mouse to freeze in place (panel 2 of the image above).
"Here, we were trying to artificially make an association between the light-reactivated memory and the foot shocks. We were just trying to artificially connect the two," said Steve Ramirez, a graduate student at the RIKEN-MIT Center for Neural Circuit Genetics in Cambridge, Massachusetts, who participated in the research, according to Discovery News.
Then, putting the mouse back into Chamber A, the mouse froze in fear, apparently remembering that its feet had been shocked in this chamber, even though the shocks took place in the completely different environment of Chamber B (panel 3 of the image above).
"They appeared to be recalling being shocked in box A, even though that had never happened," Ramirez said, according to Discovery News. "A false memory had been formed and recalled."
Given the fictional applications we've seen for this kind of work, it's easy to see the dark side of this research and its potential use in a dystopian future, but this could have some remarkable therapeutic uses in the present day. Imagine a trauma victim recalling the memories of their trauma, and then having happier memories stimulated to alleviate their stress.
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However, one thing this research also points out is that we can't always rely on our memories to be true.
"Because our study showed that the false memories and the genuine memories are based on very similar, almost identical, brain mechanisms, it is difficult for the false memory bearer to distinguish between them," said MIT neuroscientist and Nobel Laureate Susumu Tonegawa, the lead author of the study, during a Science Magazine podcast. "What we hope our current and our future findings along these lines will further allot researchers and legal experts how unreliable memory can be.
(Images courtesy: Ernie Mastroianni/DISCOVER/Getty Images, Tonegawa, et al./RIKEN-MIT/Science)
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