David Ulansey is a "Visiting Professor of Religious Studies at U.C. Berkeley, and Professor Emeritus of Philosophy and Religion at the California Institute of Integral Studies in San Francisco," and, "a scholar of the history of religions, comparative religion, and cultural history (Ph.D., Princeton Univ.)." [Source].
He is the author of "The Origins of the Mithraic Mysteries: Cosmology and Salvation in the Ancient World." I am several chapters into the book and it is fascinating. Read some of his work here.
YouTube Video Description - [Channel: rodcmp]:
In this excerpt from Entheo:genesis, Awakening the Divine Within, David Ulansey discusses shamanism and ecstasy.David Ulansey: The Principle Feature of Shamanism