Neuroscientists at the Massachusetts Institute of Technology (MIT), in the United States, have shown that it is possible to implant false memories in the brain of mice , and that many of the neurological traces of these memories are identical in nature to that of authentic memory.
“Whether it is a false memory or a true one, the brain’s neural mechanism underlying memory retrieval is the same,” explains Susumu Tonegawa, professor of Biology and Neuroscience at MIT’s Picower Institute and author of the study. published by Science. The study provides new evidence that memories are stored in networks of neurons that form memory traces (so-called engrams) from each experience we go through, a phenomenon that Tonegawa’s lab first demonstrated last year.
Episodic memories are the result of associations of various elements, objects, space and time. These associations are encoded by chemical and physical changes in neurons, as well as by modifications in the connections between neurons. Tonegawa and his colleagues are able to identify the cells that are part of a specific memory engram in a region of the brain called the hippocampus and reactivate it using a technology known as optogenetics, which allows cells to be selectively turned on or off using light.
False memories with light
As if that were not enough, the new work reveals that this technology allows to intervene in the memory process through the direct control of brain cells, specifically by implanting false memories in the brains of mice. To do this, the researchers placed the mice in a new chamber, A, but without any type of shock and, when the rodents explored it, their memory cells were labeled with canalrhodopsin. The next day, the mice were put into a very different second chamber, B, and after a while, they were given a mild foot shock and at the same instant, the researchers used light to activate the cells that encode camera A memory.
On the third day, the mice were put back into chamber A, where they were now paralyzed, even though they had never been ‘shocked there’. A false memory acted out: Mice fear room A for memory, because when they were shocked in chamber B, they were reliving the memory of when they were in chamber A.
On the other hand, that false memory appeared to compete with a true memory from chamber B, the researchers found. These mice were also paralyzed when placed in chamber B, but not as paralyzed as mice that had received a shock in chamber B without having chamber A in active memory.
Immediately after the false memories were removed, nerve activity levels were also elevated in the amygdala, the fear center in the brain that receives memory information from the hippocampus, just as they are when mice recall a genuine memory.
