It is tempting to assume that based on animal studies, which show an activation of a specific amygdalar pathway following the combination of stress and a CB-1 agonist, chronic, heavy marijuana smokers would show increased amygdalar response to affective stimuli. While we observed an increase in amygdalar activity in the contrast analyses which examined the non-smoking control subjects relative to the marijuana smokers during the tasks (NC > MJ), we did not see this response in the contrast analyses which examined the chronic, heavy marijuana smoking group relative to the non-smoking control subjects (MJ > NC). This may be a result of the stimuli being masked, which does not allow the conscious processing of the affective state displayed on the faces, although the non-marijuana smoking control subjects did demonstrate an amygdalar response. The lack of relative increased activity in amygdalar regions in the chronic, heavy marijuana smokers relative to the non-smoking control subjects may suggest a disruption early in the network responsible for detection and early processing of stimuli, which is then further reflected in the altered cingulate response to
