Dr. Mechoulam is the Israeli scientist who identified THC as the psychoactive compound in marijuana, and decades later he discovered the brain's endocannabinoid system and the endogenous neurotransmitter anandamide. He is one of the most respected Israeli neuroscientists and has been a senior advisor to the Israeli government on marijuana policy and the ethics of research with human subjects. He discussed his experiments demonstrating the neuroprotective effects of the endocannabinoid system in mice that have had traumatic injuries to the brain. He believes the neuroprotective effects of marijuana may eventually have applications for other neurological and psychiatric conditions, including Alzheimer's and Parkinson's disease.

Another fascinating discovery, one with implications for PTSD, is that the cannabinoid system is integrally related to memory, specifically to memory extinction. Memory extinction is the normal, healthy process of removing associations from stimuli. Dr. Mechoulam explained that an animal which has been administered an electric shock...