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.
The type of RNA relevant to these findings is believed to regulate a variety functions in the cell involved with the development and disease.
Some of the new snails received RNA from the trained cohort, and some, as controls, from the untrained group. These shocks amplified the snails' defensive withdrawal reflex-which it uses to protect itself. "So these snails are alarmed and release ink, but they aren't physically damaged by the shocks", he said.
The snails that received the implants had a defensive reaction of about 40 seconds after the implants, even though they had not had a reaction previously, the BBC reported.
However, speaking with The Guardian, Tomás Ryan, a studier of memory at Trinity College Dublin, is not exactly convinced that Glanzman and his team have demonstrated an ability to transfer what we consider a personal memory.
As expected, the control group of snails did not display the lengthy contraction.
The shocked snails had been "sensitised" to the stimulus. Interestingly, the researchers discovered, adding RNA from the snails that had been given shocks also produced increased excitability in sensory neurons in a Petri dish; it did not do so in motor neurons.
Speaking of what this means, Glanzman said: "What we are talking about are very specific kinds of memories, not the sort that says what happened to me on my fifth birthday, or who is the president of the USA".
He also stressed that the snails did not get hurt: "These are marine snails and when they are alarmed they release a attractive purple ink to hide themselves from predators". "While the Aplysia is a fantastic model for studying basic neuroscience, we must be very careful in drawing comparisons to human memory processes, which are much more complex". (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.
But in a new study, researchers claim to have made headway in understanding the simplest kind of memory a mollusc might form, and, with a swift injection, managed to transfer such a memory from one sea snail to another.
Glanzman and his colleagues published research in 2014 suggesting that lost memories could potentially be restored based on this concept. As a result, researchers used RNA, which is part of the epigenetic modification and part of the process of forming long-term memory.
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.