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Marijuana directly affects the area of the brain that controls these two functions that begin with the letter "M".
What are "Memory" and "Motivation"?
When someone uses marijuana, chemicals travel through the bloodstream an dquickly attach to receptors on the brain's nerve cells, which receive information from other nerve cells and chemicals. When a receptor receives information, it causes changes in the nerve cell.
One region of the brain that contains a lot of THC receptors is the hippocampus, which processes memory. When THC attaches to receptors in the hippocampus, it weakens short-term memory.
The hippocampus also communicates with other brain regions that process new information into long-term memory. In the brain, under the influence of marijuana, new information may never register -- and may be lost from memory.
Some frequent, long-term marijuana users show signs of a lack of motivation (amotivational syndrome). Their problems include not caring about what happens in their lives, no desire to work regularly, fatigue, and a lack of concern about how they look. As a result of these symptoms, some users tend to perform poorly in school or at work. Scientists are still studying these problems.