Researchers have found that memories that have been 'lost' as a result of amnesia can be recalled by activating brain cells with light. They reactivated memories that could not otherwise be retrieved, using a technology known as optogenetics.
Neuroscience researchers have for many years debated whether retrograde amnesia -- which follows traumatic injury, stress, or diseases such as Alzheimer's -- is caused by damage to specific brain cells, meaning a memory cannot be stored, or if access to that memory is somehow blocked, preventing its recall.
"The majority of researchers have favored the storage theory, but we have shown in this paper that this majority theory is probably wrong," Tonegawa says. "Amnesia is a problem of retrieval impairment."
I am driven by two philosophies: know more about the world than I did yesterday and lessen the suffering of others. You'd be surprised how far that gets you. - Neil deGrasse Tyson
Amazing and very scary at the same time. Being able to repress memories does have its purpose