The investigation of endocannabinoids leading to discovery of a new signalling system in the brain, depolarization-induced suppression of inhibition (DSI), for treatment related to brain and other medical problems is discussed. DSI, enables individual neurons to disconnect briefly from their neighbors and encode information. The results indicate that endocannabinoids are important in extinguishing the bad feelings and pain triggered by reminders of past experiences. It is suggested that abnormally low numbers of cannabinoid receptors are involved in post-traumatic stress syndrome, phobias and certain forms of chronic pains.