Sea hare discovery may enhance our understanding of learning and memory

Researchers are improving our understanding of learning by using RNA to transfer memory

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Memory is important for learning throughout life and knowing where memories are stored in the brain are vital for targeting the treatment of conditions like Alzheimers Disease. Research has traditionally held the view engrams physically store long term memory in the synaptic connections of our brains. How our minds are structured and function is unique to the individual and a product of our inherited DNA. Environmental factors are known to affect the expression of genes (epigenetic changes) and have become the focus of research concerning memory function, along with the role RNA play in coding and expressing genes. 

A research team led by Alexis Bedecarrats from the University of California tested the hypothesis the behaviour an animal learns (long term memory encoded by epigenetic changes) can be transferred by ribonucleic acid (RNA) into naive recipients, causing a learning-like behavioural change to occur. Neuroscientists have mapped all 20,000 neurons in sea hares (Aplysia californica), a marine sea slug that inhabits the tidal zones of tropical waters in the Indo-Pacific, Atlantic and Mediteranean Oceans. As part of the experiment, researchers triggered the siphon withdrawal reflex in a treatment group of sea hares, by applying a small electronic stimulus to their tails over 48 hours. RNA was then extracted from the central nervous system of the trained snails and injected into a group of naive snails. The researchers reported the engram for long term memory from the trained snails had successfully been transferred into the naive snails, because the recipients expressed the learnt behaviour of the donor, without prior experience of the exercise. In future, the importance of this study is RNA might be a transfer molecule useful for depressing, changing or improving memory.

For more detail about this study, the article is freely available via the journal Eneuro here.

Photo credit: Aplysia californica emitting ink cloud By Genny Anderson  

Reference: Jensen, K.L. Sørensen,G. Dencker,D. Owens,W.A. Rahbek-Clemmensen,T. Lever, M.B. Runegaard, A.H. Christensen ,N.R. Weikop, P. Wörtwein, G. Fink-Jensen, A. Madsen, K.L. Daws, L. Gether, U. and Rickhag, M. RNA from Trained Aplysia Can Induce an Epigenetic Engram for Long-Term Sensitization in Untrained Aplysia 

Gabrielle Ahern

Managing Editor, npj Science of Learning Community

I am based in Queensland, Australia, and have an interesting portfolio of skills, experience and qualifications in science research and content creation.