Poke a snail with a stick and it remembers for a day. Poke a snail with a stick after you've given it methamphetamine and it remembers for much longer. Getting gastropods hooked on meth perhaps sounds cruel, but Barbara Sorg and her team are among those scientists trying to figure out how the drug works in the brain to produce intense connections that feed the addiction cycle. In a study forthcoming in the Journal of Experimental Biology, the scientists show that, in snails at least, meth makes it hard to forget things that happened while on the drug. Here's the test: The snails Sorg studied can breathe two ways, through their skin underwater and also through a breathing tube they can deploy when they surface. The team kept two groups of snails—one on meth, one not—in separate tanks of shallow water. And if the snails tried to surface and breathe that way, the scientists would poke them.
By poking the snails, Sorg's team trained them to associate using the tubes with an unpleasant experience, and so keep them shut. Only the snails on speed remembered their training the following morning, and in a separate experiment it took longer for them to "unlearn" the memory [New Scientist].
The drug induces changes in the brain that last after the chemical is out of a snail's system.
"These drugs of abuse produce very persistent memories," explained Dr Sorg. "It's a learning process - drug addiction is learning unwittingly. All of these visual, environmental and odour cues are being paired with the drug" [BBC News].
Pinning down just what physical changes in the brain allow for that effect is the key to the ultimate end of this kind of research: Targeting the intense memory
associations that feed addiction as a part of drug treatment. And the research on learning and forgetting could have wider implications as well, says George Kemenes of the University of Sussex, who also does mollusk research:
"Ultimately, the humble snail could help prevent and treat memory disorders or even enhance normal memory" [BBC News].
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Image: Wikimedia Commons