WIKIMEDIA, NATIONAL INSTITUTES OF HEALTHThe brain may continue to harbor old memories, even if they can’t be recalled anymore, according to the results of a mouse study published this week (May 29) in Science. Scientists induced mice to have amnesia, then reactivated particular neurons that had been active during the formation of a memory, and the memory—fear of a cage—returned.
“Brain researchers have been divided for decades on whether amnesia is caused by an impairment in the storage of a memory, or in its recall,” Susumu Tonegawa, director of the RIKEN-MIT Center for Neural Circuit Genetics and an author of the study, said in a press release. “Our conclusion is that in retrograde amnesia, past memories may not be erased, but could simply be lost and inaccessible for recall.”
Tonegawa and his colleagues identified genetically labeled neurons—called memory engram cells—that were active in mice during the formation of a memory, in particular, learning to fear a particular cage. Then they administered a chemical to induce amnesia in the mice shortly after the training (the drug blocks synapses from strengthening), and the animals no longer exhibited ...
