Brain changes during a shamanic trance: Altered modes of consciousness, hemispheric laterality, and systemic psychobiology

摘要

There have been a number of electrophysiological and neuroimaging studies in “altered” states of consciousness including dissociative conditions, hypnosis, and meditation; however, the nature and clinical significance of trance states remain elusive. Alterations of consciousness that accompany trance can shed light on the brain networks contributing to the experience of autobiographical self; the subjective demarcation of “self” from others and reality at large; and normative vs. pathological domains of self-experience. Shamanic trance is a volitional, self-induced state of consciousness that historically served the purposes of social cohesion and healing interventions in diverse tribal settings. We present the first neurophysiological study of a normal subject, who has received extensive training in the Mongolian shamanic tradition and is capable of self-inducing a trance state without external sensory stimulation. Quantitative EEG mapping and LORETA (low resolution electromagnetic tomography) source imaging indicate that shamanic state of consciousness (SSC) involves a shift from the normally dominant left analytical to the right experiential mode of self-experience, and from the normally dominant anterior prefrontal to the posterior somatosensory mode. These findings have implications for the psychobiology of the normative conscious mode of awareness and neurophysiological processes contributing to dissociative, psychotic, and transpersonal domains of self-experience. They may be used as a foundation to bridge Western and traditional healing techniques.