Amnesia-hit patients can recall their lost memories: New study

Amnesia-hit patients can recall their lost memories: New study

Memories lost as a result of amnesia can be retrieved by activating certain brain cells with light, a new study says.

Researchers at the Massachusetts Institute of Technology (MIT) have managed to recover lost memories of a group of laboratory mice, hit by amnesia, through using a technology known as optogenetics, or the use of light to prompt action in certain nerve cells of the brain.

The findings of the study were published in the journal Science on Friday.

Lost memories had been stored within the brain cells even though the mice were seemingly unable to retrieve them, the researchers say, putting the results at odds with the long-held theory that the memory loss in amnesia is a result of problems with the storage of memory rather than the inability to recall it.

“The majority of researchers have favored the storage theory, but we have shown in this study that this majority theory is probably wrong. Amnesia is a problem of retrieval impairment,” said Susumu Tonegawa, a professor at MIT's Department of Biology and the director of the research.

The results of the research mean that “past memories may not be erased, but could simply be lost and inaccessible for recall,” the Nobel Prize-winning scientist added.

The findings reveal that memories are stored through building new connections, or synapses, among specific nerve cells, known as “memory engram cells”, in the brain and thus, the ability to recall the memory involves the augmenting of these connections, a process that can be blocked when the brain is damaged by traumatic injury or diseases such as Alzheimer’s.

Through employing optogenetics “we were able to demonstrate for the first time that these specific cells had undergone this augmentation of synaptic strength,” and thus helped mice to recall their lost memories, Tonegawa noted.

He expressed hope that the findings of the research would stimulate future studies on the biology of memory and its clinical restoration.