The main active chemical in marijuana is THC (delta-9-tetrahydrocannabinol). Researchers have found that THC changes the way in which sensory information gets into and is acted on by the hippocampus. This is a component of the brain's limbic system that is crucial for learning, memory, and the integration of sensory experiences with emotions and motivations. Investigations have shown that THC suppresses neurons in the information-processing system of the hippocampus. In addition, researchers have discovered that learned behaviors, which depend on the hippocampus, also deteriorate.
Thats an excerpt from http://www.theantidrug.com/drug_info...-marijuana.asp
, which can't possibly be controlled by the government nor blatent liars like your bullshit paper does a bad job of trying to prove.