To our knowledge, this is the first fMRI study of regional brain differences in response to the masked affective stimuli in chronic, heavy marijuana smokers and non-marijuana smoking control subjects. Results from the current investigation suggest that individuals who are chronic, heavy marijuana smokers do not appear to process affective stimuli in the same way as those who do not smoke. This is true despite the fact that the stimuli used in the current investigation were administered below the level of conscious awareness, suggesting a disruption early in the neural circuit responsible for affective processing. Given the behavioral alterations and difficulty in inhibiting inappropriate responses often seen in marijuana smokers, this finding may have implications for decision making, which may result in negative consequences. The ability to accurately perceive emotion and identify the affective states of others is critical for effective communication. Further research is needed to determine the long-term effect of marijuana on affective processing and the potential for altering these neural changes through moderation or abstinence from the drug.
