A few years ago, I had occasion to host for a presentation Bertha Madras, Ph.D., a professor of psychobiology at Harvard Medical School (https://www.mcleanhospital.org/profile/bertha-madras). Dr. Madras spoke about the science of marijuana -- the knowns and the "known unknowns." What was crystal clear from her presentation is that permanent physiological changes occur in the brain development of (a) fetuses exposed to marijuana through their mothers, and (b) individuals engaged in early (i.e., teen/pre-teen) and heavy use. The effects on the formation of their amyglada and hippocampus were clearly visible, resulting in reduced connectivity. Below are just a handful of the 70+ slides from her presentation that, again, focused only on the science of marijuana.