This brain imaging (EEG) study (n=37) found that the shamanic practitioners showed significant differences to control participants on an altered states of consciousness scale (OAV) and EEG measures. Their brainwaves resembled that of earlier data on those under the influence of psychedelics but still were identified as unique, often stronger, patterns.
“Psychedelics have been recognized as model interventions for studying altered states of consciousness. However, few empirical studies of the shamanic state of consciousness, which is anecdotally similar to the psychedelic state, exist. We investigated the neural correlates of shamanic trance using high-density electroencephalography (EEG) in 24 shamanic practitioners and 24 healthy controls during rest, shamanic drumming, and classical music listening, followed by an assessment of altered states of consciousness. EEG data were used to assess changes in absolute power, connectivity, signal diversity, and criticality, which were correlated with assessment measures. We also compared assessment scores to those of individuals in a previous study under the influence of psychedelics. Shamanic practitioners were significantly different from controls in several domains of altered states of consciousness, with scores comparable to or exceeding that of healthy volunteers under the influence of psychedelics. Practitioners also displayed increased gamma power during drumming that positively correlated with elementary visual alterations. Furthermore, shamanic practitioners had decreased low alpha and increased low beta connectivity during drumming and classical music and decreased neural signal diversity in the gamma band during drumming that inversely correlated with insightfulness. Finally, criticality in practitioners was increased during drumming in the low and high beta and gamma bands, with increases in the low beta band correlating with complex imagery and elementary visual alterations. These findings suggest that psychedelic drug-induced and non-pharmacologic alterations in consciousness have overlapping phenomenal traits but are distinct states of consciousness, as reflected by the unique brain-related changes during shamanic trance compared to previous literature investigating the psychedelic state.“
Authors: Emma R. Huels, Hyoungkyu Kim, UnCheol Lee, Tarik Bel-Bahar, Angelo V. Colmenero, Amanda Nelson, Stefanie Blain-Moraes, George A. Mashour & Richard E. Harris
The eventual analysis of data was done with that of 18 shamanic practitioners (shamans) and 19 control (age- and sex-matched) participants. The average age was 56 and the shamans were practicing for an average of 20 years were doing about 13 healing sessions done every month.
During the EEG measurement, both groups listened to a drumming recording (25 minutes) from Michael Harner. A one hour version of this can be found here.
The study consisted of listening to the drumming recording, classical music recording, baseline measures (start and end) with eyes open and closed, an Altered States of Consciousness scale (OAV), and cognitive tests that will be discussed in a separate paper.
The shamans were asked to perform healing during the experiment and entered an altered state of consciousness to heal a client (not present at the study site).
The OAV data was also compared to that of 43 studies of participants on a variety of psychedelics (ketamine, psilocybin, and MDMA) that were used to validated the scale (Studerus, Gamma & Vollenweider, 2010)
The shamans scored significantly higher than the other participants on 8 of the 11 domains of the OAV during shamanic healing (drumming recording).
Compared to the psychedelics data, shamans scored higher on 1) complex imagery, 2) experiences of unity, 3) spiritual practice, and 4) insightfulness. See supplemental table 2 for all the correlations.
The shamans had significantly higher scores on gamma power during drumming than the other participants. Gamma waves or power is associated with working memory, attention, and perceptual grouping and is also raised for participants on psychedelics (e.g. DMT; Pallavicini et al., 2021) or meditation.
The shamans also had higher scores (greater connectivity) in the low beta band during drumming, and decreased low alpha connectivity.
Finally, the shamans also had higher low & high beta and gamma criticality as measured using the pair correlation function (PCF).
This study was the largest neuroimaging study to date that looked at shamans, in the shamanic state. The differences found were similar to, and sometimes even greater, than those experiencing a high dose of psychedelics. The data suggest that shamans are able to reach a state of higher criticality, which can be likened to being more aware or have a richer conscious experience.