0954 GMT July 22, 2018
That might sound like science fiction or remind some readers of debunked ideas from decades past. But it's serious science: In a new study, researchers at the University of California, Los Angeles (UCLA) extracted RNA, a genetic messenger molecule, from one snail and implanted it in another snail, according to foxnews.com.
Then, for good measure, they dribbled that same RNA over a bundle of loose neurons in a petri dish.
In both experiments, the recipient — either the snail or the petri-neurons — remembered something the donor snail had experienced.
The memory was simple, the kind of thing even a snail's reflex-based, brainless nervous system can hold onto: The shock of an electric zap in the butt.
When Aplysia californica sea snails get zapped in the tail, they send signals through their simple nervous systems: Retract the parapodia!
At that signal, the little fleshy flaps hanging from their little snail bellies retract.
Shock a snail often enough, and it will remember that it's been getting zapped a lot lately, and its parapodia will retract for longer and longer periods of time.
That's a simple behavior based on a simple memory. And in the new paper, published in the journal eNeuro, the UCLA scientists showed that they can suck that memory out of one snail in the form of RNA and stick it in another.
Lead study author David Glanzman, a neuroscientist and integrative biologist at UCLA, said, "All [that the recipients] were exposed to was RNA from a trained animal [a snail with the zap memory] or an untrained animal, or in some cases, just the chemical we used to deliver the RNA.”
When the RNA came from a snail that hadn't been zapped, the memory recipients acted ‘naïve’, retracting their parapodia only briefly after a zap, as if no more zaps were coming. But when snails were exposed to the RNA from a snail that had been zapped, they retracted their parapodia for longer periods after zaps.
Glanzman said, "This is important, because it said it's not just [any implanted RNA] that is producing widespread excitability in neurons.”
Instead, snails with RNA from other snails that had been shocked — and from only those snails — acted just like they had received those initial ‘teaching’ tail shocks themselves.
Glanzman and his colleagues were able to see the effect on an even more basic level in their bundle of snail neurons in a petri dish.
When the researchers bathed the neurons in RNA from a trained snail for 24 hours, then doused the cells in the chemical messenger that means ‘butt zap’ (in snails, that chemical is serotonin), the neural cells fired wildly, telling their nonexistent parapodia to retract.
When the neurons were bathed in RNA from untrained snails, the nerve cells' reactions were shorter and less intense.
Right now, there's a lot more work to be done before scientists can say they've found the stuff of memory.
Importantly, the type of memory transferred here, the sensitization of a reflex, is among the most basic that exists.
Glanzman said the next step in this research is to attempt similar feats of memory transfer involving more-complex kinds of memories in more-complex animals, like mice.