Amnesia Possibly Curable by Stimulating Certain Neurons With Light

Researchers at the Massachusetts Institute of Technology (MIT) detailed a method for recovering memories lost to amnesia.

According to the Washington Post, the scientists equated amnesia to misplacement of memories rather than utter loss. For their study, published in the journal Science, they stimulated certain neurons in mice's brains to help them recover memories.

"The majority of researchers have favored the storage theory, but we have shown in this paper that this majority theory is probably wrong," study co-author Susumu Tonegawa, the Picower Professor in MIT's Department of Biology, said in a news release. "Amnesia is a problem of retrieval impairment."

Stimulating, or controlling, neurons with light is a practice known as optogenetics, which was central to the new research. For it to work scientists single out neurons and introduce a particular protein to make them sensitive to blue light, in turn subjecting them to being flicked on and off like a switch.

"If you test memory recall with natural recall triggers in an anisomycin-treated animal, it will be amnesiac, you cannot induce memory recall," Tonegawa said. "But if you go directly to the putative engram-bearing cells and activate them with light, you can restore the memory, despite the fact that there has been no LTP.

"We are proposing a new concept, in which there is an engram cell ensemble pathway, or circuit, for each memory.

"This circuit encompasses multiple brain areas and the engram cell ensembles in these areas are connected specifically for a particular memory."

Unaffiliated with the study, a memory expert at the University of California, Los Angeles called the paper "groundbreaking."

"This groundbreaking paper suggests that these changes may not be as critical for memory as once thought, since under certain conditions, it seems to be possible to disrupt these changes and still preserve memory," Alcino Silva said in the release. "Instead, it appears that these changes may be needed for memory retrieval, a mysterious process that has so far evaded neuroscientists."