Scientists achieved a 'memory transplant' in snails – what does that mean for the human brain?

Transferring memories might sound like an impossible feat, yet that is just what scientists in California recently appeared to have achieved with the humble snail.

The widely-publicised work has raised questions about whether our own memories too could be transferred from person to person, or from person to machine. Indeed the prospect that a person’s life experiences could be downloaded to machine has become an increasingly serious subject for discussion in recent years.

In the recent California study, scientists gave the tails of one group of marine snails electric shocks, causing their defensive reaction to become more pronounced.

They then transferred genetic material called ribonucleic acid (RNA) from this group to individuals that had not received the shocks. The startling finding was that this second group began to show a similar defensive response, as though the memory of the shocks had been transferred.

Researchers have suggested that the work could improve understanding of human conditions that affect memory, such as Alzheimer’s disease.

Memories have often been thought to reside in the synapses – the gaps between nerve cells or neurons; however, the work on snails appears to indicate that, instead, memories could be contained within RNA, which is involved in the production of proteins controlling many biochemical activities.

Is it possible to transfer human memory?

Despite what was done with the snails, transferring memories from person to person is a long way off, assuming it could ever be achieved. It remains, says Professor Matt Jones, a neuroscientist who works on memory at the University of Bristol in the United Kingdom, within the “realms of science fiction”. The nature of memory coding, residing in changes in the connections between specific brain cells, makes this impossible, he said.

“It would be quite near impossible to detect how a particular memory was encoded in an individual and to transfer it to another individual,” he added.

It is a view echoed by Professor Christian Holscher, who researches neurodegenerative disorders at Lancaster University in the United Kingdom.

“You would need to know what each individual synapse is doing in the brain, and there are more synapses than there are stars in the galaxy. It’s impossible,” he said.

“The architecture, the way the brain is designed, makes it impossible to even know exactly where memory is located and to copy that and transfer it to another brain.”

Prof Holscher does not see the work on snails as genuinely involving memory transfer, branding it “a bit of a party trick”. “They induced a change in the state of the animal and used that signalling to affect another animal, which shows a similar change in the neuronal response. It’s just show,” he said.

“It doesn’t mean that the specific content of memory can be transferred. It’s just a general response these animals will show. A generic response, a reflex. It’s really hyped.”

There have, however, been numerous experimental studies on animals that are more like humans than snails are that have attempted to gain a better understanding of how and where memories are stored, a key step before human memories could be transferred or downloaded to computer. It has been shown that stimulating a part of the brain called the hippocampus can “insert” memories into rat brains.

Scientists Theodore Berger, of the University of Southern California, and Samuel Deadwyler, of Wake Forest School of Medicine, in North Carolina, United States, found that specific memories were associated with particular patterns of electrical signals, in terms of where and when they took place in the brain.

Researchers have also wired together the brains of rats so that information could be transferred from one to another, allowing them to co-operate.

And what about copying it to a computer?

Moving closer to science fiction is the suggestion that it will be possible to download memories to a computer, allowing a person to live for ever in machine form. It would require a recreated brain with approximately 100 trillion connections between the brain’s 90 million or so neurons. This is a long way off: today mapping just a fly’s brain takes two years.

Nonetheless, Google’s director of engineering, Ray Kurzweil, has said that by the end of this century, people will be able to live in machine bodies.

The idea of downloading memories now has “a whiff of feasibility” thanks to the advent of neural networks and machine learning, according to Prof Jones.

“I don’t think that could then be transferred back into organic material. It’s feasible a digital replica of someone’s memory content could be generated,” he said.

Artificial neural networks are the computer equivalents of animal brains and are capable of learning. Prof Jones said there was “fascinating research” with neural networks that can interact with humans, such as when they have been used with individuals having treatments like cognitive behavioural therapy.

“If the virtual therapist was informed by a virtual memory, then he, she or it may become even more effective,” he said.

An affair to remember

Being able to download memories could prove useful for treating conditions, such as dementia, that involve memory loss.

“If it became possible to repair the brain to an extent that it could receive back the memories you had temporarily downloaded, that would be worthwhile,” said Prof Jones.

Treatments that could repair the brain or even slow or stop the progression of degenerative conditions appear to be a long way off, however, with 99.6% of candidate drugs for Alzheimer’s tested between 2002 and 2012 found to be ineffective.

“There’s a lot of research going on. Quite a lot of it is quite exciting, but much of it isn’t going in the direction of prevention, which is what we should be doing,” said Professor David Smith, professor emeritus of pharmacology at the University of Oxford and co-founder of the Oxford Project to Investigate Memory and Ageing.

As work on technology that could one way lead to memories being downloaded continues, Prof Jones warned that new regulation is important to prevent things going too far.

“Like many of these technologies, it could be abused … We don’t want to turn one person into another,” he said.

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