Transferring reminiscences from one residing factor to a different sounds just like the plot of an episode of “Black Mirror.” But it might be extra practical than it sounds — not less than for snails.
In a paper published Monday in the journal eNeuro, scientists on the University of California-Los Angeles reported that once they transferred molecules from the mind cells of skilled snails to untrained snails, the animals behaved as in the event that they remembered the skilled snails’ experiences.
David Glanzman, a professor of neurobiology at U.C.L.A. who’s an writer of the brand new paper, has been learning Aplysia californica, a sea snail, and its capacity to make long-term reminiscences for years. The snails, that are about 5 inches lengthy, are a helpful organism for learning how reminiscences are fashioned as a result of their neurons are giant and comparatively straightforward to work with.
In experiments by Dr. Glanzman and colleagues, when these snails get slightly electrical shock, they briefly retract their frilly siphons, which they use for expelling waste. A snail that has been shocked earlier than, nonetheless, retracts its siphon for for much longer than a brand new snail recruit.
Recently, the scientists realized that even once they interfered with their skilled snails’ mind cells in a manner that ought to have eliminated the reminiscence fully, some vestige remained. They determined to see whether or not one thing past the mind cells’ connections to one another — particularly, RNA — might be hanging on to the reminiscence.
You would possibly keep in mind RNA from highschool biology: It is greatest identified for ferrying messages between the genome and the remainder of the cell. But scientists have step by step realized that there’s extra to RNA than enjoying messenger.
There are some sorts of RNA that, as an alternative of carrying messages, assist swap genes on and off. They have been proven to be concerned in long-term reminiscence in snails, mice and rats, by their capacity to affect chemical tags on DNA. These tags in flip affect whether or not a gene might be turned on in an organism.
To perceive what was taking place of their snails, the researchers first extracted all of the RNA from the mind cells of skilled snails, and injected it into new snails. To their shock, the brand new snails saved their siphons wrapped up for much longer after a shock, virtually as in the event that they’d been skilled.
Next, the researchers took the mind cells of skilled snails and untrained snails and grew them within the lab. They bathed the untrained neurons in RNA from skilled cells, then gave them a shock, and noticed that they fired in the identical manner that skilled neurons do. The reminiscence of the skilled cells appeared to have been transferred to the untrained ones.
Importantly, when the researchers gave the brand new snails a drug that retains chemical tags from being added to DNA, the reminiscence didn’t switch. That is in keeping with different experiments which have steered that blocking the formation of such tags blocks the formation of long-term reminiscence in snails and a few rodents, mentioned Dr. Glanzman. That means that what they’re seeing is in actual fact associated to reminiscence, and never one thing else to do with the inflow of recent RNA.
Earlier reporting on reminiscence analysis
The analysis has echoes of research from the 1960s involving flatworms. Back then, scientists indulged in slightly vicarious cannibalism: They chopped up flatworms skilled to reply to gentle, then fed the stays to different flatworms, to see whether or not the useless flatworms’ reminiscences would switch. Oddly sufficient, it appeared like they did. But the outcomes have been troublesome to duplicate. The subject moved on.
Dr. Glanzman mentioned that that is the primary examine because the flatworm work to suggest that reminiscences could be transferred in such a manner. “It feels like I’m way out on a limb, frankly,” he mentioned.
The crew’s findings are a good distance nonetheless from being utilized to individuals and the way our reminiscences type. But Dr. Glanzman hopes others will attempt to replicate the experiments in different animals, probably opening the door sooner or later to understanding how RNA and genetic tags on DNA might be concerned in reminiscence.