Some forms of memory may leave traces in RNA molecules, and an experiment on marine mollusks suggests that they can be transplanted.
The transfer of memories from one individual to another, like files to copy and move on a stick, is a classic science fiction movie theme. Precisely for this reason they are discussing the results obtained by a Californian neurobiologist, who claims to have transplanted a very basic form of memory between two marine mollusks through a simple injection, moving not nerve cells, but RNA molecules . The research was published in the scientific journal eNeuro.
If what was confirmed by David Glanzman, a neurobiologist at the University of California in Los Angeles, was confirmed, it would mean that some elementary forms of learned experiences leave traces not in the connections between neurons, as commonly accepted, but in molecules that play a key role in coding and in the regulation of gene expression.
A TRAUMATIC MEMORY
Glanzman has solicited with moderate electric shocks the tail of some specimens of Aplysia californica , a sea snail was used as a model in learning of the studies because it presents a neural transmission similar to that which occurs between our nerve cells. The shocks caused in the molluscs a defensive mechanism that has contracted the body for a few tens of seconds.
Later, when these snails were simply touched, they repeated the same prolonged form of defense, unlike the untrained molluscs, which only contracted for a second.
THE TRANSPLANT
At this point Glanzman extracted RNA samples from the nervous system of sensitized snails with an injection and transferred it to some mollusks that had not undergone any stress. RNA (ribonucleic acid) is a complex molecule, crucial for regulating gene expression, protein assembly and other fundamental biological tasks.
The "receiving" snails exhibited the same defensive behavior as the "donors", contracting to the touch for 40 seconds even if they had never suffered any shock. The same reflex has also been found on simple sensory snail cells in vitro. RNA transplantation from snails that had not had electrical shocks did not give the same results.
SCIENCE, NOT SCIENCE FICTION
For Glanzman, the experiment shows that this specific form of engram , that is of mnemonic trace, is conserved in RNA and not in the contact points between neurons: if the opposite were true, it would not have been possible to transfer any memory. However, that headline is a very primitive type of memory, which has nothing to do with autobiographical memories or with the memory of what you learned at school.
The Aplysia is an effective model for the basic neuroscience, but caution should be exercised in comparisons with the complex human memory. The most skeptical of neuroscientists prefer to speak of an instinctive elementary behavior that would have created a sort of genetic switch , a transferable modification, in the animal organism ... something that still sounds more reasonable than "transplanting memories".