a young man in my neighborhood recently shared a story with me about his experiences with the plant salvia divinorum, which he received as a birthday present. unfortunately for him, nobody took the time to discuss the reverse tolerance effect that salvia is known to have, leading to some short-lived chaos for this young gentleman. later that day, while exploring the internet for more information on the neurological mechanisms behind reverse tolerance, i came across a page that discussed reverse tolerance in regard to marijuana use which was (obviously) quite heady but coincided with my personal theory regarding psychedelic drugs. the exact mechanism(s) by which many psychedelic drugs interact with the cns is remains largely unknown, (though there are many theories out there). according to this article, over time, the human brain develops its inherent capacity to become high and that the use of marijuana merely potentiates this ability, (as opposed to causing it). i have always thought similarly about other drugs, such as lsd, that rather than being the sole cause of an altered state of consciousness, these drugs prime the human body to activate pre-existing neurological pathways, and the capacity to achieve this altered state of awareness increases as we become more familiar with it (acid flashbacks, anyone?). the ability to control these pathways is not yet a voluntary process, at least not for anyone i know personally, but i would consider it well within the realm of possibilities of the human mind.