Phenomenology and brain measures during cognitive trance: a case study.

Cognitive trance is a volitional and self-induced modified state of consciousness inherited from shamanic traditional practices that can be practiced by any individual. Little is known about its phenomenology and neural correlates. We here describe the case of an expert who underwent resting-state EEG, TMS-EEG and FDG-PET during normal wakefulness and cognitive trance. Phenomenological questionnaires were filled after each session. EEG analyses included spectral power and complexity measures. For TMS-evoked potential, diversity index and global mean field power were computed. For PET, global brain metabolism difference between rest and trance was measured. During trance, the participant felt more joy, visual imagery, body image, and an altered experience. She reported higher absorption and dissociation, with five-fold time-scale distortion. Trance was associated with increased spectral power in all frequency bands. Entropy also showed an increase, especially in posterior regions. TMS-EEG showed modifications in cortical reactivity, while PET revealed no significant difference in brain metabolism. Cognitive trance induced a modified state of consciousness characterized by changes in behavior and neurophysiological processes.