Classic Hallucinogens and Mystical Experiences : Phenomenology and Neural Correlates
Frederick S. Barrett and Roland R. Griffiths
The following chapter will appear in the Springer text “Behavioral Neurobiology of
Psychedelic Drugs”, in the series “Current Topics in Behavioral Neuroscience” that is
edited by Adam L Halberstadt, Franz X Vollenweider, and David E Nichols
Current Topics in Behavioral Neuroscience, 2017 March 26.
DOI: 10.1007/7854_2017_474
Abstract
This chapter begins with a brief review of descriptions and definitions of mystical-type experiences and the historical connection between classic hallucinogens and mystical experiences. The chapter then explores the empirical literature on experiences with classic hallucinogens in which claims about mystical or religious experiences have been made. A psychometrically validated questionnaire is described for the reliable measurement of mystical-type experiences occasioned by classic hallucinogens. Controlled laboratory studies show that under double-blind conditions that provide significant controls for expectancy bias, psilocybin can occasion complete mystical experiences in the majority of people studied. These effects are dose-dependent, specific to psilocybin compared to placebo or a psychoactive control substance, and have enduring impact on the moods, attitudes, and behaviors of participants as assessed by self-report of participants and ratings by community observers. Other studies suggest that enduring personal meaning in healthy volunteers and therapeutic outcomes in patients, including reduction and cessation of substance abuse behaviors and reduction of anxiety and depression in patients with a life-threatening cancer diagnosis, are related to the occurrence of mystical experiences during drug sessions. The final sections of the chapter draw parallels in human neuroscience research between the neural bases of experiences with classic hallucinogens and the neural bases of meditative practices for which claims of mystical-type experience are sometimes made. From these parallels, a functional neural model of mystical experience is proposed, based on changes in the default mode network of the brain that have been observed after the administration of classic hallucinogens and during meditation practices for which mystical-type claims have been made.
Keywords : Psilocybin, Hallucinogens, Meditation, Mystical experiences , Neural model, Default mode network, Medial prefrontal cortex, Posterior cingulate, Angular gyrus , Inferior parietal lobule
Contents
1 Introduction…………………………………………………………………………………………………………
2 What Are Mystical Experiences?…………………………………………………………………………..
3 Historical Use of Indigenous Hallucinogens …………………………………………………………..
4 Experimental Evidence of Mystical Experiences with Psilocybin ……………………………..
5 The Mystical Experience Questionnaire …………………………………………………………………
6 Mystical Experiences, Classic Hallucinogens, and Therapeutic Interventions …………….
7 Are Mystical Experiences Reducible to Neural Processes? ………………………………………
8 Hallucinogens and Meditation as Tools to Investigate the Neural Correlates of Mystical
Experiences…………………………………………………………………………………………………………
9 Hallucinogens, Meditation, Mystical Experience, and the Default Mode
Network ……………………………………………………………………………………………………………..
9.1 The Medial Default Mode Network……………………………………………………………..
9.2 The Lateral Default Mode Network……………………………………………………………..
10 Toward a Neural Model of Mystical Experiences……………………………………………………
11 Conclusion ………………………………………………………………………………………………………….
References ………………………………………………………………………………………………………………….
1 Introduction
Reports of mystical-type experiences date back many centuries (e.g., in the case of Rumi or St. Teresa of Avila), if not millennia (i.e., in the case of Plotinus) (Stace 1960a). Mystical experiences have occurred in the course of structured spiritual or religious practices as well as in cases in which there was no direct intention to have such an experience. Mystical experiences are uniquely interesting and important to study because they are sometimes associated with abrupt, substantial, and sustained changes in behavior and perception (Miller and C’de Baca 2001). Furthermore, the authoritative sense of interconnectedness and sacredness that defines such experiences suggest that mystical experiences may be foundational to the world’s ethical and moral systems (Huxley 1947). Despite their apparent importance, the unpredictability and low probability of “naturally occurring” mystical-type experiences, whether they occur in religious or nonreligious contexts, has made them inherently difficult to study in controlled empirical research.
While there are countless reports of profound spiritual and mystical experiences that have occurred in the absence of psychoactive substances, historical evidence abounds for the role of psychoactive substances in ceremonial approaches to facilitating such experiences (Schultes et al. 2001). Further, descriptions of naturally occurring mystical experiences (Stace 1960b) are strikingly similar to profound spiritual experiences occasioned by hallucinogenic substances (Roberts 2001).
Experimental investigations have begun to utilize classic hallucinogens to study the reliability, characteristics, subjective nature, and behavioral consequences of mystical-type experiences (Pahnke 1963; Griffiths et al. 2006, 2011; Garcia-Romeu et al. 2015). Classic hallucinogens are a structurally diverse group of compounds that bind at 5-HT2A serotonin receptors and produce a unique profile of changes in thoughts, emotions, and perceptions, often including profound alterations in the perception of reality, that are rarely experienced except in dreams, naturally occurring mystical experiences, and acute psychosis. The use of classic hallucinogens makes the study of mystical experiences more tractable because classic hallucinogens can be administered under double-blind conditions and can occasion mystical experiences with high probability (Griffiths et al. 2006, 2011). Classic hallucinogens allow for prospective and controlled exploration of such experiences, and provide a degree of neurobiological specificity and mechanistic understanding that is not possible in correlational or descriptive studies, or in reviews of present-day or historical case reports.
The following section of this chapter reviews descriptions and definitions of mystical-type experiences. Evidence of the historical connection between classic hallucinogens and mystical experiences is then presented. The chapter then reviews empirical evidence of mystical experiences occasioned by classic hallucinogens and the potential therapeutic benefits of such experiences. The chapter ends with an exposition of a functional neural model of mystical experience that is based on changes in the default mode network of the brain that have been observed after the administration of classic hallucinogens and during meditation practices which are sometimes associated with mystical-type experiences.
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