Chapter 2 - Marijuana’s Acute Effects

Summary

Science explains how marijuana produces the experience of being high after Herkenham mapped location of the densest concentrations of CB1 receptors. The hippocampus, amygdala, and basal ganglia/cerebellum have especially dense cannabinoid receptors and THC impacts the functions produced by these areas in conspicuously noticeable ways. The hippocampus produces short term memory, an important element in learning. Reduced working memory is the most documented cognitive impairment caused by acute marijuana use. The endocannabinoid system is also uniquely responsible for forgetting negative experiences. The amygdala modulates anxiety, appetites, the sense of novelty and the hypothalamus. When THC stimulates the amygdala, most people experience relaxation, hunger (“munchies”) and altered sensory experience due to dishabituation to stimuli. Hypothalamic modulation by the amygdala results in reduction of the stress response, leading to the “chill” of being high. And genetic differences in CB1 density determines aspects of temperament. Supranormal stimulation of CB1 receptors in the basal ganglia reduces spontaneous motor activity and THC stimulation of the cerebellum reduces fine motor control and alters the sense of time and driving skills. The experience of being high is the culmination of altered brain function in the above areas with the highest CB1 density.