Scientists Successfully Eliminate, Retrieve Memories, Mouse Study

Scientists have now discovered a way to retrieve memories that were lost to stress, brain injury or other related diseases.

A team of scientists from the Massachusetts Institute of Technology (MIT) were successful at retrieving lost memories in mice when they tried to activate brain cells by light.

Neuroscientists for years have debated over the effects of retrograde amnesia which is usually caused by a traumatic brain injury.

The loss of memory could be attributed to specific brain cells being damaged, meaning memory cannot be stored. While others believe that amnesia is caused when the access to the memory is blocked as a result people are unable to recall a specific incident.

"The majority of researchers have favoured the storage theory, but we have shown in this paper that this majority theory is probably wrong," said Susumu Tonegawa, professor at the Massachusetts Institute of Technology.

"Amnesia is a problem of retrieval impairment," Tonegawa said.

For the study, team used a technology called optogenetics where a virus is injected into the neurons to produce a light sensitive protein. This would then activate the cells in response to light.

The mice were put in a special chamber were they were given mild electric shocks. So each time, the mice were put in the chamber they would freeze in fright since they had already begun to associate with the feeling of being shocked while being in that space.

Once their training was complete, some of the mice were given anisomycin which would induce retrograde amnesia. When they were placed in the chamber they no longer froze since they had no memory of the incident.

However when the scientists used the pulses of light to activate the embedded memory the mice would then recollect their previous experience with the chamber and then freeze again.

"Our conclusion is that in retrograde amnesia, past memories may not be erased, but could simply be lost and inaccessible for recall," said Tonegawa.

"These findings provide striking insight into the fleeting nature of memories, and will stimulate future research on the biology of memory and its clinical restoration," he added.