The debate over marijuana, the Cannabis sativa plant which contains the chemical tetrahydrocannabinol (THC), has been a part of American culture for decades. Regardless of anecdotal evidence or personal experimentation, some scientific facts about the specific effects of THC are known. For example, THC binds with cannabinoid receptors in the hippocampus, which is responsible for the organization and formation of memory. This binding decreases neuron activity, and so the hippocampus can have difficulty processing memory data. There is also evidence that long-term use can permanently damage the hippocampus, but many long-term users refute that idea.
Regardless, the effects of marijuana use on cognitive performance and function remains unclear; many studies have found conflicting information and results, leading to no specific understanding. However, evidence shows that: immediate cognitive function and performance can be reduced by marijuana use; that light use does not seem to create these effects permanently; that heavy use tends to affect performance during the time of usage, but the effects decrease as long as more THC is not introduced into the body. A 2001 controlled experiment showed that while performance was significantly slowed during THC use, the actual results of cognitive tests remained steady; this supports the idea that the immediate effects of THC serve to limit sensory input, but do not affect cognition or abstract reasoning abilities to a great extent.