Transferring memories from one individual to another, as if they were files to copy and move on a stick, it is a classic theme from science fiction movies. For this reason they are doing discuss the results obtained from a California neurobiologist, who claims to have transplanted a very basic form of memory between two marine molluscs through a simple injection, moving not nerve cells, but RNA molecules. The research was published in the scientific journal eNeuro.

If the allegation made by David Glanzman, a neurobiologist at the University of California, Los Angeles, were confirmed, it would mean that some elementary forms of lessons learned do not leave traces in the connections between neurons, as commonly accepted, but in the molecules that play a key role in the encoding and in regulating gene expression.

A traumatic memory. Glanzman called moderate electric shock tail of some specimens of Aplysia californica, a sea slug used as a model in studies on learning because it presents a neural transmission similar to that which occurs between our nerve cells. The tremors caused in shellfish a defensive mechanism that the body has contracted for a few tens of seconds.

Later, when these snails were simply touched, they repeated the same form of prolonged defense, as opposed to the untrained molluscs, which are contracted for a second.

Transplantation. At this point Glanzman extracted with an injection of RNA samples from the nervous system of sensitized snails and transferred in some molluscs that had not undergone any stress. The RNA (ribonucleic acid) is a complex molecule, which is crucial to regulate gene expression, the assembly of proteins and other important biological tasks.

Snails "receiving" exhibited the same defensive behavior of the "donor", contracting for 40 seconds at the touch even though they had never suffered any shock. The same reflex was also found on simple sensory cells in vitro snail. The RNA transplant from snails that had not had electric shocks did not give the same results.

Science, not science fiction. For Glanzman, the experiment shows that this specific form of engram, that the memory trace, is preserved in RNA and not the contact points between neurons: if it had been the other way, it would not be possible to transfer any memory. That head is still a very primitive type of memory, which has nothing to do with autobiographical memories or the memory of what you have learned in school.

The Aplysia is an effective model for the basic neuroscience, but caution should be exercised nell'azzardare comparisons with the complex human memory. The more skeptical among neuroscientists prefer to speak of an elementary instinctive behavior that would create a kind of genetic switch, a downloadable modification in the animal ... which still sounds more reasonable "memories transplant".

From Focus