Melatonina e catecolaminas plasmáticas, atividade elétrica cerebral e atividade autonômica cardíaca durante experiências anômalas em um contexto religioso

Abstract

Mediumship and spirit possession are cultural phenomena found in several societies worldwide. In Brazil, Spiritism (a tradition where mediumship is emphasized) is the third largest religious denomination. The “absorption hypothesis” (the association of marked increases in focused attention withconcomitant decreases in self-awareness) is one of the most widely accepted neuropsychological explanatory theory for these experiences, although there are yet other tentative suggestions about possible neurophysiological underpinnings. The present study aimed to investigate physiologic correlates of non-pathological dissociative experiences in twenty female Spiritist mediums with several years of socially sanctioned practice compared to twenty female non-medium control subjects from the same religious context. We measured measured electroencephalographic (EEG) spectral power in frontal electrodes within theta, alpha and beta bandwidths, cross-regional cortical coherences and heart rate variability (HRV) parameters in three different moments: before, during and after mediumistically speaking. We also measured the plasma levels of hormones and neuroactive substances, as well as vital signs, in two different moments: before and immediately after mediumistic communication. Mediums had significantly greater increases in heart rate and in plasma concentrations of noradrenaline, thyroid-stimulating hormone (TSH), prolactin and creatineposphokinase (CPK) compared to non-mediums controls. The mediums had greater EEG beta power on some electrodes in all phases of the experiment, greater EEG theta power on one electrode at the communication phase and greater EEG alpha power on one electrode at the post-communication phase. Moreover, during communication, the mediums showed an autonomous nervous system shift in favor of sympathetic activity compared to a shift in favor of parasympathetic activity in the control group, which had signs of relaxation similar to a meditative state. No significant group-effect was noted for melatonin, cross-regional cortical coherences or HRV parameters from five-minute sample periods one hour before and one hour after the event. No condition effects (within-group comparisons) were detected in any group for any of the electroencephalographic parameters. No ictal EEG pattern was observed, except for one participant in the mediums group that, although lacking a history of epilepsy, had an ictal pattern in all phases of the experiment. We theorize that mediums had brief arousal as a result of a Stroop-like interference effect. Findings from this study reinforce the concept that the pathological/non-pathological dissociation may have different physiological implications and that absorption could have a mechanistic role in anomalous sensorial experiences such as mediumship. Likewise, the present data corroborate the ideas that sociocultural systems may affect cardiac autonomic regulation in some individuals with a proclivity for absorption, and that cognitive control processes may be engaged during these experiences. Finally, our findings argue against the idea of rising of melatonin levels as a necessary correlate of mediumship.