Now we can erase painful memories
Targeting small numbers of "fear" neurons could erase traumatic memories and help people overcome drug addiction, research suggests.
But the technique has "huge" ethical implications, the Canadian 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.
In real life, Dr 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-producing a certain brain protein. By genetically removing the targeted neurons, a specific memory could effectively be erased, without affecting other memories.