Published: Wed, May 16, 2018
Medicine | By Douglas Stevenson

Transplanting memory accomplished successfully in snails

Transplanting memory accomplished successfully in snails

The marine snails or Aplysia Californica were given minor electric shocks by the scientists only after proper administration of the shocks. He thinks that a behavioral response was triggered in the slugs when the genetic material was transferred. In the 1940s, Canadian psychologist Donald Hebb proposed memories are made in the connections between neurons, called synapses, and stored as those connections grow stronger and more abundant.

"If memories were stored at synapses, there is no way our experiment would have worked", he said, the BBC reported. When tapping the snails, the ones in shock training contracted their bodies for nearly 50 seconds to defend themselves. When they were shocked, the snails that weren't injected with RNA curled for only a few seconds, the way all snails do when they haven't been trained. Tsai, who recently co-authored a major review on memory formation, called Glanzman's study "impressive and interesting" and said a number of studies support the notion that epigenetic mechanisms play some role in memory formation, which is likely a complex and multifaceted process. In the years that followed, many scientists were unable to recreate the initial experiments that gave rise to the idea.

Once the reflex action had been established in the trained snails, they were euthanised and their abdominal ganglia removed.

Some of the new snails received RNA from the trained cohort, and some, as controls, from the untrained group.

A team of neuroscientists have managed to find a way to transfer memories from one individual to another via injection, but only in snails so far. They curled up for about 40 seconds, as if they had remembered how to respond to the stimulus.

Next, researchers extracted RNA from the trained and untrained snails. They have been shown to be involved in long-term memory in snails, mice and rats, through their ability to influence chemical tags on DNA. But scientists have gradually realized that there is more to RNA than playing messenger. RNA from shocked snails also enhanced a subset of synapses between sensory and motor neurons in vitro, suggesting it was indeed the RNA that transported the memory, Glanzman explains.

Transplanting memory accomplished successfully in snails
Transplanting memory accomplished successfully in snails

However UCLA's work seems to contradict this.

He also stressed that the snails did not get hurt: "These are marine snails and when they are alarmed they release a lovely purple ink to hide themselves from predators".

Glanzman says that in his next experiments he will attempt to identify the RNAs involved, and he has an idea for the mechanism, too.

The UCLA professor of integrative biology holds a different view, believing that memories are stored in the nuclei of neurons.

In their paper, Glanzman and colleagues say their results raise many new questions about the mechanics of memory storage and the nature of the engram. "But if we're right, we're just at the beginning of understanding how memory works".

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