Can We Retrieve Memories Lost to Alzheimer's?
Scientists have recovered memories in mice. What about humans?
Scientists at the Massachusetts Institute of Technology have found a way to retrieve old memories in mice who have the early symptoms of Alzheimer's disease.
The online journal Nature published the results of an experiment studying the behavior of mice that had been genetically altered to develop Alzheimer's symptoms.
“The important point is, this is a proof of concept," The Washington Post quoted MIT scientist Susumu Tonegawa as saying. "That is, even if a memory seems to be gone, it is still there. It’s a matter of how to retrieve it." Tonegawa was one of the researchers on the study; MIT graduate student Dheeraj Roy was the paper’s lead author.
Healthy and genetically altered mice were put in a chamber and given a foot shock. When they were returned to the chamber an hour later, all showed signs of fear — demonstrating that they remembered what had happened earlier. Several days later, the genetically altered mice showed no reaction when they were returned to the chamber, meaning they had forgotten their previous experience. The normal mice once again froze in fear.
Hope for Humans
The researchers then used a technique called optogenetics — optical stimulation of brain cells — to tag cells with a light-sensitive protein to store specific memories. When they shone a light on the brain cells that stored the memory of the fearful experience, the mice instantly showed signs of fear, indicating that their memory of it had been reactivated.
Optogenetics has not been used in humans, but the study offers hope that similar treatments may be developed. The revelations have “shattered a 20-year paradigm of how we’re thinking about the disease,” Rudy Tanzi, a Harvard neurology professor who is not involved in the research, told The Boston Herald.
“Nothing could be more important in thinking about the diseases that will plague modern Western society in the next 50 years,” Dr. Lee Schwamm, executive vice chair of neurology at Massachusetts General Hospital, who is also not involved in the study, told the Herald. "It’s not just that there’s no cure, there’s not even a very good treatment.”
Other experts cautioned that any application to humans with Alzheimer's — if even possible — would be years away.
