Scientists gave pond snails the amphetamine crystal meth to explore the memory-related brain processes that get humans so hooked on the drug.

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Human meth users experience sensations of happiness and high self-esteem that help make the drug extremely addictive. Scientists suspect that such cravings may be tied to powerful "pathological memories" that make such highs difficult to forget.

"We were not trying to addict the snails," said study co-author Barbara Sorg, a biochemist at Washington State University in Pullman. "We were trying to see how meth might create a better memory in the very early