It is a nightmarish science fiction scenario, in which two people’s memories can be swapped between their brains.
But fiction has become reality, after neuroscientists were able to transfer a memory from one animal into another.
The memory was the recollection of being given a mild electric shock, in sea slugs zapped repeatedly for two days.
When material from their brains was transferred into sea slugs which had never been shocked in their lives, they reacted exactly the same way to the weak touch of a wire.
The results suggest that memories can be physically transferred by injection, and follow claims from similar experiments in the 1960s that this could lead to ‘memory pills’ or jabs in the future.
While experts urge caution over similar previous studies, the authors of the latest findings, from the University of California in Los Angeles (UCLA) say they could lead to a treatment to block unwanted memories – just like in the film Eternal Sunshine of the Spotless Mind.
Science fiction has become reality, after neuroscientists were able to transfer a memory from one animal into another. Researchers say the finding could lead to a treatment to block unwanted memories – just like in the film Eternal Sunshine of the Spotless Mind (pictured)
The study, led by professor David Glanzman at UCLA, says its results offer ‘dramatic support’ for the idea that memory can be stored in ribonucleic acid, or RNA – the ‘biochemical cousin’ of DNA which is used to copy and transport our genetic code.
It states: ‘Our results suggest that RNA could eventually be used to modify, either enhance or depress, memories.’
The idea of swapping memories between brains first became popular in the 1960s, following experiments by James McConnell, who trained flatworms to scrunch up to flashes of light by giving them electric shocks.
Nicknamed ‘McCannibal’, he chopped up these flatworms and fed them to other worms, which then displayed the same fear of light.
Further experiments suggested untrained rats given RNA injections from trained rats could find their way through mazes better.
The results overturned the conventional view that memory was carried only in the junctions, or synapses, between brain cells. Instead it could be stored in RNA, leading to further experiments in animals from octopuses to kittens.
While the research had fallen slightly out of fashion, researchers are becoming interested again.
Professor George Kemenes, who has carried out similar research at the University of Sussex, said: ‘Memory transfer research has been controversial in the past because some of the results seen in animals could not be replicated.
‘But this robust study, done by experts with extensive knowledge of the brains and nervous systems of sea slugs, is extremely convincing in determining that memories are mediated by RNA.
Sea slugs were given a mild electric shock repeatedly for two days. When material from their brains was transferred into sea slugs (pictured) which had never been shocked in their lives, they reacted exactly the same way to the weak touch of a wire (stock image)
‘It might give rise to novel types of treatment to eliminate memories related to post-traumatic stress syndrome in people or to alleviate memory loss caused by dementia, but that could be a long time away.’
Memories may been transferred in the study, which is published in the journal eNeuro, through micro-RNA.
This tiny RNA had previously been dismissed as ‘junk’ because it does not play the same role as ‘messenger’ RNA in copying and carrying genetic code.
The frightened sea slugs learned to pull their gills into their body in response to an electric shock, then had cells removed from their brains and spun rapidly in a centrifuge to extract the RNA.
Untrained slugs, which should have been unafraid of an electrical wire, also retracted their gills after being injected in the necks with RNA from the frightened slugs. Other slugs, not given the injections, did not react.
The full findings of the study were published in the journal eNeuro.
A recent study led by researchers from Dartmouth and Princeton has shown that people can intentionally forget past experiences by changing how they think about the context of those memories.
The researchers showed participants images of outdoor scenes, such as forests, mountains and beaches, as they studied two lists of random words.
The volunteers deliberately manipulated whether the participants were told to forget or remember the first list prior to studying the second list.
Right after they were told to forget, the scans showed they ‘flushed out’ the scene-related activity from their brains.
But when the participants were told to remember the studied list rather than forget it, this flushing out of scene-related thoughts didn’t occur.
The amount people flushed out scene-related thoughts predicted how many of the studied words they would later remember, which shows the process is effective at facilitating forgetting.
To forget those negative thoughts coming back to haunt you, researchers suggest trying to push out the context of the memory.
For example, if you associate a song with a break-up, listen to the song in a new environment.
Try listening to it as you exercise at the gym, or add to a playlist you listen to before a night out.
This way, your brain will associate with a positive feeling.
If a memory of a scene from a horror film haunts you, watch the same scene during the daytime.
Or watch it without sound but play a comedy clip over the top.