A new study published in the US journal Science revealed the possibility of reviving lost memories. The research was conducted on mice by Massachusetts Institute of Technology and Riken Brain Science Institute in Japan.
Researchers used a method called optogenetics, where scientists select certain neurons and introduce a special protein through an engineered virus. Blue light pulses were then used to stimulate “memory engrams,” and memories are formed in activated neurons. The protein in these neurons are activated by light, enabling researchers to turning them on and off at will.
“Past memories may not be erased, but could simply be lost and inaccessible for recall,” said Susumu Tonegawa, director of Riken Brain Science Institute, Japan.
Scientists created a bad memory in mice by shocking them in an enclosure. Scientists injected a drug annisomycin into the mice which alters memory formation, resulting in a condition to retrograde amnesia. The mice stopped being afraid of the enclosure — until researchers used a blue light to activate their neurons. Then , the fear response returned.
Researchers believe that “lost” memories leave engrams in the brain. The memories were revived as certain connections in the brain were unaffected by the drug but inaccessibly without the light treatment. These connctions were storing information relating to the shock treatment as well. Tonegawa said that the findings will stimulate future research on the biology of memory and its clinical restoration.
However, the findings are unlikely to help humans to recover from amnesia anytime soon. A neuroscientist at MIT and co-author of the study Tomas Ryan stated that it is difficult to be done in humans beings due to ethical reasons: the procedure is invasive and the memory needs to be tagged in the brain before they are learned. Scientists feel that the method could be applied to humans in the future through further research.
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