Have Sea Slugs Proved That Memories Can be Transferred?
Neuroscientists have revealed the potential that memories might be captured by RNA, meaning that memories can actually be transferred.
The study shows that a molecule, when taken from one sea slug and injected into another, appeared to transfer a rudimentary memory between the two, reports Science News.
Most neuroscientists believe long-term memories are stored by strengthening connections between nerve cells, but the results prove differently, instead offer the idea that some types of RNA molecules, and not linkages between nerve cells, are key to long-term memory storage.
“It’s a very controversial idea,” said co-author David Glanzman, a neuroscientist at UCLA. When poked or prodded, some sea slugs will reflexively pull their siphon, a water-filtering appendage, into their bodies. Using electric shocks, Glanzman and his colleagues sensitised sea slugs to have a longer-lasting siphon-withdrawal response – a very basic form of memory. The team then extracted RNA from those slugs and injected it into slugs that hasn’t been sensitised, they showed the same long-lasting response to touch as their shocked companions.
RNA molecules come in a variety of flavours that carry out specialised jobs, so it’s not yet clear which kind of RNA is responsible for the effect. However, he believes that it could be the handful of RNA varieties that don’t carry instructions to make proteins, the typical job of most RNA.
But, scientists remain apprehensive, even those who question whether the strength of nerve cell connections is the key to long-term memory storage. The fact that untrained slugs become more sensitive to touch after RNA injection is “amazing,” adds biochemist Tomas Ryan of Trinity College Dublin, who wasn’t part of the study. “But it doesn’t go far enough to say that the memory has been transferred.”