A new study strongly suggests that at least some memories are stored in the genetic code, and that the genetic code can act as a memory soup. Suck it from an animal and paste the code into a second animal, and that second animal can remember things that only the first animal knew.
That might seem like science fiction or remind some readers of discredited ideas of past decades. But it’s a serious science: in a new study, researchers at the University of California, Los Angeles (UCLA) extracted the RNA, a genetic messenger molecule, from a snail and implanted it in another snail. Then, as a measure, they sprayed that same RNA onto a packet of loose neurons in a Petri dish. In both experiments, the recipient, either the snail or the petri neurons, remembered something that the donor snail had experienced.
Memory was simple, the kind of things that even a brain-free nervous system based on snail reflexes can cling to: the impact of an electric shock on the backside. [10 things you did not know about the brain]
When Aplysia californica sea snails get trapped in the tail, they send signals through their simple nervous system: retract the parapodia!
Before that signal, the small fleshy flaps that hang from their small snail bellies are retracted.
Shock a snail often enough, and remember that it has been zapping a lot lately, and its parapodia will retract for longer and longer periods of time. It is a simple behavior based on a simple memory. And in the new document, published today (May 14) in the journal eNeuro, UCLA scientists showed that they can absorb that memory from one snail in the form of RNA and paste it into another.
“Everything [that the receptors] were exposed to was RNA from a trained animal [a snail with zap memory] or an untrained animal, or in some cases, just the chemical we used to administer the RNA,” David Glanzman said. Lead author of the study, David Glanzman, neuroscientist and integrative biologist at UCLA.
When the RNA came from a snail that had not been deactivated, the memory receptors acted “naively”, retracting their parapodia only briefly after a zap, as if no more shots were coming. But when the snails were exposed to the RNA of a snail that had been deactivated, they retracted their parapodia for longer periods after the zaps.
“This is important, because it says that it is not just [any implanted RNA] that produces widespread excitability in neurons,” Glanzman told Live Science.
On the other hand, snails with RNA from other snails that had been impacted, and only those snails, acted as if they had received the initial shocks of “teaching” themselves.
Glanzman and his colleagues could see the effect at an even more basic level in their package of spiral neurons in a Petri dish. When the researchers bathed the neurons in RNA from a trained snail for 24 hours, they then sprayed the cells on the chemical messenger which means “hit!” (in snails, that chemical is serotonin), the neuronal cells shot violently, telling their nonexistent parapodia to retract.
When the neurons were bathed in RNA from untrained snails, the reactions of the nerve cells were shorter and less intense.
A long simmering debate
“This paper describes potentially transformative findings about whether memory could be transplanted through transcriptomic transfer [genetics],” said Sathya Puthanveettil, a neuroscientist at the Scripps Research Institute in California who studies memory but did not participate in the study. .
There has been a long simmering debate in neuroscience about whether essential memory units are stored primarily in the “transcriptome” (long molecules within cells are also used to register genes) or the “connectome” (the network). of links between nerve cells).
The transcriptome was more popular in the 20th century, when scientists tried and failed to hunt “memory RNA” in more crude experiments that looked generally like Glanzman’s. Eventually, however, that idea fell into disfavor, and more and more research and funding turned to the connectome. Today, there are several active attempts to map the connectome in humans, and some researchers even suggest that the connectome could be used to preserve human memories after death, although this has not yet been proven.
But studies with conectomas, including the mapping of the entire Caenorhabditis elegans worm connectome, have failed to produce conclusive and predictive evidence of memory matter, so some scientists have also looked less favorably at that work.
In fact, Glanzman is a bit of a partisan in that debate, and said he sees his experiment as evidence on his side.
“In my opinion, we are spending too much time and money studying synaptic connections, and not much money studying these changes based on RNA and epigenetics,” or changes in how cells interact with their genetic code, he said.
This apparent demonstration of the content of memory in snails represents a powerful argument for that cause. Still, it’s important to keep in mind that this is just an experiment.
“At the moment, we do not have much mechanical information about how this memory transfer is achieved,” Puthanveettil told Live Science. “We would need more confirmation experiments to validate these findings in other models.”
In other words, scientists do not know at all how this transfer happened, and it is possible that something is happening in this experiment that they do not understand.
At this time, there is much more work to be done before scientists can say they have found the memory material. It is important to emphasize that the type of memory transferred here, the sensitization of a reflex, is among the most basic that exist.
Glanzman said the next step in this research is to try similar memory transfer feats that involve more complex types of memories in more complex animals, such as mice.