effects of a wide variety of psychoactive substances, with over 45 articles documenting its use as of mid-2015. A follow-up study demonstrated lack of tolerance of the psychological effects of repeated closely spaced doses of DMT, making it unique among classical psychedelics. More than half of Strassman's volunteers reported profound encounters/interaction with nonhuman beings while in a dissociated state. Strassman has conjectured that when a person is approaching death or possibly when in a dream state, the body releases a relatively large amount of DMT, mediating some of the imagery survivors of near-death experiences report. But there are no data correlating endogenous DMT activity to non-drug-related altered states of consciousness. He also has theorized that the pineal gland may form DMT under certain conditions. In 2013 researchers first reported DMT in the pineal gland microdialysate of rodents. Strassman has detailed his research in his book DMT: The Spirit Molecule, and co-produced a 2010 documentary film of the same name based on this book. He has also conducted similar research on psilocybin, a psychedelic alkaloid found in hallucinogenic mushrooms. In unpublished studies, he administered doses of up to 1.1 mg/kg, nearly three times the doses considered "psychedelic" in contemporary clinical research with this compound. Religious models for integrating DMT experiences Inspired by visions he had when he took LSD in the early 1970s, Strassman began studying Buddhism as a young man. He trained for 20 years in Zen Buddhism, received lay ordination in a Western Buddhist order, and led a meditation group of the order. But his work with DMT led him to feel Buddhist models may not be the most suitable way for us to explain and integrate the spiritual dimensions of the DMT experience: Strassman suggests that DMT experiences may most closely resemble those found in the Hebrew Bible's model of prophecy: Some of Strassman's experimental participants say that other entities can resemble creatures more like insects and aliens than anything in the Bible. As a result, Strassman wrote that these experiences of his experimental participants "also left me feeling confused and concerned about where the spirit molecule was leading us. It was at this point that I began to wonder if I was getting in over my head with this research." He has also hypothesized that endogenous DMT experiences could be the cause of alien abduction experiences. See also Luis Eduardo Luna Terence McKenna Dennis McKenna Jeremy Narby