Scientists for the first time “pumped” the memory of one slug into the brain of another mollusk
© Flickr / prilfish
MOSCOW, May 15 (Itar-Tass) – RIA Novosti. California sea hares, poisonous slugs, can inherit memories of relatives if one enters into their nerve centers RNA molecules from the brain of another mollusk. This radically changes the views of scientists about the nature of memory, says an article published in the journal eNeuro.
Scientists have learned when and where memories are formed
"The discovery that the transplantation of RNA from one slug to the other transfers the memory of the first individual to it, has become the most convincing proof that memories can be stored not only inside synapses, but also in purely chemical form. All this suggests that in the future we will be able to suppress the old memory or write new information to the brain with RNA", – write David Glanzman (David Glanzman) and his colleagues from the University of California in Los Angeles (USA).
For a long time scientists believed that the memory in our brain is stored in the form of sets of electrical impulses, which exchange cells in the so-called hippocampus, the brain memory center. The situation changed dramatically in 2012, when the neuroscientists of MIT discovered in the hippocampus special nerve cells, the so-called engram neurons, which turned out to be peculiar "cells" Memory where individual memories are stored.
This led many scientists to believe that our memory is either purely chemical or electrochemical in nature, and that many violations in its work are associated with breakdowns in cellular systems that control metabolism in neurons. Guided by this idea, biologists recently were able to suppress, and then restore a specific memory in several mice, and then restore forgotten knowledge in humans.
Scientists have proved that forgotten memories can be returned
All these experiments, as Glanzman says, did not answer the main question – how exactly are memories stored and whether they can be changed without interfering with the work "electrical" parts of the brain, as did the authors of past experiments.
His team tried to find the answer to this question by experimenting with Californian sea hares (Aplysia californica) – large poisonous slugs living in the waters of the Pacific Ocean. "Brain" these mollusks consist of a relatively small number of large neurons, which makes them an ideal tool for solving the mysteries of the work of the nervous system.
Past experiments on sea hares, as the neurophysiologist notes, have led many of his colleagues to believe that memory can not be stored in synaptic endings of nerve cells, as the experiments of 2012 indicated, but inside the body of neurons. Their carrier, respectively, may be some protein molecules or filaments "trash" RNA, present in neurons in large quantities.
Neuroscientists returned lost memories to mice with the help of light
Glantzman and his team checked whether this was actually the case, having grown two colonies of Aplysia californica, one of which lived in relative safety, and the second – periodically suffered electric shocks. Two days later, when the mollusks developed a peculiar "Afghan syndrome" in relation to this procedure, scientists extracted from their body nerve nodes, isolated their RNAs and introduced these molecules into the neurons of the first group of slugs.
As it turned out, this "downloading" memory really works. After RNA injection, the mollusks began "cringe", waiting for another electric shock in "hour x", despite the fact that they had never experienced this painful procedure before. Worked and the inverse "therapy" – RNA molecules slugs from the control group relieved the rest of the animals from the memory of the electric shock.
Similar results, as Glantzman points out, suggest that either all or at least part of the memory is stored in engram cells in the form of a specific set of RNA molecules and changes in the DNA wrap that arise from their "transplantation" in new neurons. This, in turn, leaves the hope that bad memories and mental illnesses can be treated in the future with the help of such injections, scientists conclude.