Snail memory study offers hope to trauma victims

LOS ANGELES Tue Apr 26, 2011 7:32pm EDT

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LOS ANGELES (Reuters) - Scientists have managed to erase memories in common marine snails, a finding that could lead to new treatments for human victims of post-traumatic stress disorder, the researchers said on Tuesday.

In a study conducted at the University of California at Los Angeles, neuroscientists demonstrated that blocking the activity of a key enzyme kept the Aplysia snails from cringing when touched in a once-painful spot.

They reasoned that blocking the same enzyme in people might help erase painful memories and could even have implications for Alzheimer's disease and drug addiction, two other ailments tied to memory.

The study, reported by UCLA on Tuesday, was due to be published on Wednesday in the Journal of Neuroscience.

"This has implications for psychiatric disorders that are related to memory," David Glanzman, senior author of the study, said in a statement. "Post-traumatic stress disorder is a hyper induction of a long-term memory that won't go away."

Glanzman, a UCLA professor of biology, physiology and neurobiology, said the findings offered a way to target and weaken certain traumatic memories in humans, if not necessarily eliminate them altogether.

While the Aplysia snail, common to marine waters off California, has 20,000 neurons in its central nervous system, compared to about 1 trillion for a human, the UCLA scientists say the gastropods are similar to people in how they learn and form memories.

For the study, Glanzman's team first applied electric shocks to the snails, then gently prodded an organ in their mid-section. The snails responded by contracting for 50 seconds.

A week later, the scientists touched the snails in the same spot, and again the creatures contracted -- this time for at least 30 seconds. For the scientists, that was evidence the mollusks had formed a negative memory to being shocked and prodded.

The research team then injected the snails with a compound that blocked the action of an enzyme called PKM, which is associated with memory.

When they poked the snails 24 hours later, the creatures barely moved, suggesting the bad memory of being poked had been dulled.

(Editing by Julie Steenhuysen, Steve Gorman and Peter Bohan)

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