Science sets sights on '˜bad memory' brain cells

Targeting small numbers of 'fear' neurons could erase traumatic memories and help people overcome drug addiction, research in Canada suggests.

Kate Winslet and Jim Carrey in a scene from Eternal Sunshine Of The Spotless Mind. Picture: Moviestore/Rex/Shutterstock

But the technique has “huge” ethical implications, the scientist developing it has warned.

Removing all bad memories could prevent us learning from our mistakes, said Dr Sheena Josselyn, from the University of Toronto.

The research has echoes of science fiction movie Eternal Sunshine Of The Spotless Mind, in which an estranged couple erase each other from their memories.

Josselyn’s team has succeeded in both activating and erasing fear-based memories in mice.

Previous research had highlighted collections of neurons known as “engrams” that fire in a particular pattern when a memory is created.

The Canadian researchers found certain neurons compete to be recruited to an engram underlying a fearful memory.

Of the millions of neurons in the brain, only a few were necessary to form a memory associated with fear or a threatening situation. The scientists also found it was possible to flag up those neurons engaged in fear memory by over-production of a certain brain protein.

By genetically removing the targeted neurons, a specific memory could effectively be erased, without affecting other memories.

Further work in mice showed cocaine addiction could be overcome by wiping out emotional memories associated with taking the drug.

Speaking at the annual meeting of the American Association for the Advancement of Science (AAAS) in Boston, Josselyn said: “Our findings suggest that one day it could be possible to treat people with PTSD [post-traumatic stress disorder] by erasing these traumatic memories.

“In these people, the memories are intrusive and disrupt their everyday lives.

“However, there could be potential downsides, especially when applied to people who would like to get rid of a ‘bad memory’, such as a messy break-up.

“We all learn from our mistakes. If we erase the memory of our mistakes, what is to keep us from repeating them?”

She added: “There are huge ethical implications and considerations. Just because something is possible, does not mean that it should be done. Our studies provide a proof-of-principle.”