Memory is one of the most important aspects of creatures with higher intelligence, and it was recently found that animals can mentally replay past events. Altering the processes that control memory could be enormously useful — as in restoring positive memories — or enormously harmful — as in deleting memories of events that were vital to learning. That’s technology’s lack of a moral imperative though — the outcome depends on how it’s used.
UCLA biologists report they have transferred a memory from one marine snail to another, creating an artificial memory, by injecting RNA from one to another. This research could lead to new ways to lessen the trauma of painful memories with RNA and to restore lost memories.
“I think in the not-too-distant future, we could potentially use RNA to ameliorate the effects of Alzheimer’s disease or post-traumatic stress disorder,” said David Glanzman, senior author of the study and a UCLA professor of integrative biology and physiology and of neurobiology. The team’s research is published May 14 in eNeuro, the online journal of the Society for Neuroscience.
RNA, or ribonucleic acid, has been widely known as a cellular messenger that makes proteins and carries out DNA’s instructions to other parts of the cell. It is now understood to have other important functions besides protein coding, including regulation of a variety of cellular processes involved in development and disease.
The researchers gave mild electric shocks to the tails of a species of marine snail called Aplysia. The snails received five tail shocks, one every 20 minutes, and then five more 24 hours later. The shocks enhance the snail’s defensive withdrawal reflex, a response it displays for protection from potential harm. When the researchers subsequently tapped the snails, they found those that had been given the shocks displayed a defensive contraction that lasted an average of 50 seconds, a simple type of learning known as “sensitization.” Those that had not been given the shocks contracted for only about one second.
The life scientists extracted RNA from the nervous systems of marine snails that received the tail shocks the day after the second series of shocks, and also from marine snails that did not receive any shocks. Then the RNA from the first (sensitized) group was injected into seven marine snails that had not received any shocks, and the RNA from the second group was injected into a control group of seven other snails that also had not received any shocks.
Remarkably, the scientists found that the seven that received the RNA from snails that were given the shocks behaved as if they themselves had received the tail shocks: They displayed a defensive contraction that lasted an average of about 40 seconds.
Scientists know more about the cell biology of this simple form of learning in this animal than any other form of learning in any other organism, Glanzman said. The cellular and molecular processes seem to be very similar between the marine snail and humans, even though the snail has about 20,000 neurons in its central nervous system and humans are thought to have about 100 billion.
In the future, Glanzman said, it is possible that RNA can be used to awaken and restore memories that have gone dormant in the early stages of Alzheimer’s disease. He and his colleagues published research in the journal eLife in 2014 indicating that lost memories can be restored.