Psychedelics, entropic brain theory, and the taxonomy of conscious states: a summary of debates and perspectives.

Given their recent success in counseling and psychiatry, the dialogue around psychedelics has mainly focused on their applications for mental health. Insights from psychedelic research, however, are not limited to treating mental health, but also have much to offer our current understanding of consciousness. The investigation of psychedelic states has offered new perspectives on how different aspects of conscious experience are mediated by brain activity; as such, much more has been learned about consciousness in terms of its phenomenology and potential mechanisms. One theory that describes how psychedelics influence brain activity is the "entropic brain theory" (EBT), which attempts to understand conscious states-normal and psychedelic-in terms of "brain entropy." Given its wide explanatory reach, this theory has several implications for current debates in consciousness research, namely the issue of whether consciousness exists in levels vs. dimensions; whether the psychedelic state is itself a "higher" level of consciousness; and if so, whether psychedelics could be used to treat disorders of consciousness. To understand how psychedelics could possibly treat a minimally conscious or vegetative patient, one must first understand EBT and how this theory intersects with these ongoing debates. Thus, this article offers a formal summary of EBT, distilling its core principles and their implications for a theoretical model of consciousness. In response to their proposed use in treating disorders of consciousness, we emphasize the importance of "set" and "setting" in ascertaining the therapeutic value of psychedelics for vegetative and/or minimally conscious patients.