Amnesia has long been at the heart of scientific debates. For some, memory loss caused by head trauma, stress, or illnesses like Alzheimer’s is the result of damage to specific brain cells. For others, it is explained by a problematic access to memories.
Researchers at the Massachusetts Institute of Technology, Learning and Memory Research Center in the United States (MIT) used optogenetics in mice, which involves adding proteins to neurons to enable them to be activated by light, to demonstrate the existence of these memory cells in the hippocampus of the brain.
The formation of a memory
The researchers imagined the existence in the brain of a network of neurons which, activated during the formation of a memory, cause physical or chemical changes called engrams. “If these groups of engram neurons are then reactivated by an image, a smell or a flavor, all the recorded memory should come back,” the researchers explain.
“The majority of scientists favor the theory of destruction of information storage, but this research shows that this is probably wrong,” said Professor Susumu Tonegawa, Nobel laureate in Medicine in 1987 and co-author of the study. . “Amnesia is a memory recovery problem,” he says.
Information inaccessible
The results of this experiment revealed that amnesia is characterized by problematic access to memories.
“This research has made it possible to dissociate the mechanisms for storing memory from those allowing it to be formed and retrieved. This shows that in some forms of amnesia the memory of the past may not have been erased but is simply inaccessible, ”says Thomas Ryan, a researcher at MIT, the lead co-author of this research.
“This work sheds a surprising light on the nature of memory and will stimulate future research on the biology of memory and its clinical restoration”, concludes Professor Susumu Tonegawa.
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