To support this the fMRI and PET studies measure cerebral blood flow and glucose metabolism , which are indirect markers for dopaminergic projections . Both of these systems are inconclusive in showing THC effects on the striatum a dopaminedense system . They refer instead to cognitive tasks for this proof , and find effects of THC on motor response inhibition AKA , when motor inhibition is being suppressed within the ACC and right inferior frontal cortex which I believe relates to goaloriented activity . This is clearly just a small point of the study , being one of its 137 citations . But it ' s fascinating to analyze the sources that contribute to this review . for reference , the study I mention is Borgwardt , S . J . et al . Neural basis of 9 tetrahydrocannabinol and cannabidiol effects during response inhibition . Biol . Psychiatry 64 , 9669732008 .