Eisch adds that much more work must be done before scientists can reach any definitive conclusions about the benefits and costs of marijuana. First and foremost, researchers need to establish that THC has the same positive effects as the synthetic HU210. Then they must develop more sophisticated experiments to firm up the correlation between neuron growth in the hippocampus and emotional balance. Finally, she says, scientists must understand why cannabinoids have a different effect on the brain than other addictive drugs. Although his findings point to potential benefits of smoking pot, Zhang says that he does not endorse its use. "Marijuana has been used for medicine and recreation for thousands of years," he says. "But it can also lead to addiction." He says his group's next studies will examine this more unpleasant side of the drug. Other addiction researchers will be keenly interested in the results, because this cannibinoid acts so differently on the hippocampus than other drugs. KEEP ROLLING GUYS