Researchers Transfer Memories Between Snails

Henrietta Strickland
May 15, 2018

The UCLA team suggests their research might one day allow us to, as the study states, "modify, enhance, or depress memories".

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.

The type of RNA relevant to these findings is believed to regulate a variety functions in the cell involved with the development and disease.

In an experiment to test the idea, Glanzman implanted wires into the tails of California sea hares, or Aplysia californica, and gave them a series of electric shocks. (For a control, the team also took RNA from non-shocked snails and injected into naive snails.) When tapped on the siphon 24 hours later, snails that got RNA from shocked snails withdrew their siphon and gill for significantly longer (almost 40 seconds) than did snails that got RNA from non-shocked animals (less than 10 seconds). Sticking electrodes in the snail's tail and shocking it makes this defensive response last longer, tens of seconds, and sometimes up to nearly a minute. Those that had not been given the shocks contracted for only about one second.

Senior study author David Glanzman, from UCLA's Department of Integrative Biology and Physiology, pointed out that the snails used in the experiment were not hurt in any way.

Scientists extracted RNA from the nervous systems of the snails that received the shocks and injected it into a small number of marine snails that had not been sensitised in this way.

As expected, the control group of snails did not display the lengthy contraction. Therefore, RNA from a trained animal might be capable of producing learning-like behavioral change in an untrained animal. Some dishes had RNA from marine snails that had been given electric tail shocks, and some dishes contained RNA from snails that had not been given shocks.

When a marine snail is given electric tail shocks, its sensory neurons become more excitable. Moreover, a specific cellular adjustment that underlies sensitization in Aplysia, sensory neuron hyperexcitability, can be reproduced by exposing sensory neurons in vitro to RNA from trained animals.

See, some researchers think memories are stored in the synapses (the spaces between nerve cells). (Each neuron has several thousand synapses.) Glanzman holds a different view, believing that memories are stored in the nucleus of neurons.

The researchers said that the cells and molecular processes in the marine snails are similar to those in humans, despite the fact that the snail has about 20,000 neurons in its central nervous system and humans are thought to have about 100 billion.

"The next step is to sequence the RNA from the trained animals and the RNA from the untrained animals in order to determine the specific species of RNA that transmit the memory", Glanzman said. He and his colleagues published research in the journal eLife in 2014 indicating that lost memories can be restored.

"These basic science approaches to explore this are very, very useful for identifying some of the foundation building blocks, if you will, of how this might contribute to the more complicated memories that you think of in humans", said Newbern.

Co-authors are Alexis Bédécarrats, a UCLA postdoctoral scholar who worked in Glanzman's laboratory; and Shanping Chen, Kaycey Pearce and Diancai Cai, research associates in Glanzman's laboratory.

Other reports by Click Lancashire

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