The U.S. Drug Enforcement Administration (DEA) stated in its online article "Marijuana" (accessed on Dec. 29, 2006):

“As THC enters the brain, it causes a user to feel euphoric — or ‘high’ — by acting in the brain’s reward system … in the same way that nearly all drugs of abuse do, by stimulating brain cells to release the chemical dopamine. …

Marijuana’s damage to short-term memory seems to occur because THC alters the way in which information is processed by the hippocampus, a brain area responsible for memory formation.”

Dec. 29, 2006