British Journal of Anaesthesia
April 13, 2018
Phillip E. Vlisides, Tarik Bel‐bahar, Amanda Nelson et al.
117 citations
Subanaesthetic doses of ketamine produce altered states of consciousness dominated by dissociative experiences such as disembodiment and ego transcendence, along with sensory disturbances. These subjective effects occur alongside a broad decrease in low-frequency brain electrical activity, with the largest reductions in alpha power (8–12 Hz) in parietal and occipital regions. Specific decreases in alpha power were identified in the precuneus and temporal-parietal junction, brain areas involved in multisensory integration, body representation, and consciousness. The findings suggest that modulation of these temporal-parietal loci may be a candidate mechanism for ketamine's psychoactive effects.
Frontiers in Human Neuroscience
March 18, 2021
Emma R. Huels, Hyoungkyu Kim, UnCheol Lee et al.
51 citations
Shamanic practitioners in trance show brain changes that overlap with but are distinct from those caused by psychedelic drugs. In 24 practitioners and 24 controls, EEG recordings during shamanic drumming revealed increased gamma power linked to visual changes, decreased low alpha and increased low beta connectivity, reduced gamma-band signal diversity tied to insightfulness, and increased criticality in beta and gamma bands correlating with complex imagery. Practitioners' altered-state scores matched or exceeded those of people on psychedelics. The findings indicate that shamanic trance and psychedelic states share some phenomenal features but produce unique neural signatures.
Neuroimage
June 1, 2023
Rui Dai, Tony E. Larkin, Zirui Huang et al.
49 citations
Three different psychedelics—nitrous oxide, ketamine, and lysergic acid diethylamide—produce a common pattern of brain network changes despite having distinct molecular mechanisms and delivery methods. Each drug reduced connectivity within brain networks and enhanced connectivity between networks. Specifically, all three increased connections between the right temporoparietal junction and bilateral intraparietal sulcus, and between the precuneus and left intraparietal sulcus. These regions lie within the posterior cortical "hot zone," an area thought to mediate the qualitative aspects of experience. The findings identify a biologically plausible candidate for the subjective effects of both classical and non-classical psychedelics.
Commun Biol
December 19, 2023
Rui Dai, Zirui Huang, Tony E. Larkin et al.
7 citations
At concentrations that produce psychedelic effects, nitrous oxide reduces the functional differentiation—the distinctness of activity patterns—within frontoparietal and somatomotor cortical networks. This suggests that the gas alters brain network organization, potentially contributing to its consciousness-altering properties. The finding points to a neural mechanism underlying the non-ordinary state induced by nitrous oxide, involving reduced specialization of key brain regions.
Journal of Restorative Medicine
January 1, 2025
Matthew Hicks, Richard E. Harris
3 citations
Shamanic healing, a practice rooted in transcultural worldviews involving interaction with the spirit world, shows potential benefits and a low risk of harm when used as a clinical intervention. A review of medical literature found sixteen relevant publications, including one clinical trial, two case series, and ten case reports. The authors conclude that shamanic healing is feasible to investigate further, though more research is needed to clarify its benefits.
Frontiers in Psychology
January 1, 2025
Emma R. Huels, Lily Carter, Gang Xu et al.
Shamanic journeying, an ancient spiritual practice, produces dynamic changes in heart function measurable through heart rate variability (HRV). In a single subject, drumming initiation decreased heart rate and increased HRV measures, while shapeshifting increased heart rate and certain HRV indicators. Qigong meditation also increased HRV measures, with greater changes in some metrics than drumming initiation. These findings suggest shamanic journeying involves widespread cardiac and physiological changes that can be tracked visually and via ultra-short-term HRV.
Research Square
January 12, 2026
Niloufar Pouyan, Chelsea M Kaplan, Tony E. Larkin et al.
Subanesthetic nitrous oxide (N2O) alters visual experience by reconfiguring large-scale brain networks rather than changing early visual processing. In a placebo-controlled fMRI study with 13 healthy adults, participants viewed a flashing checkerboard and rated visual intensity and unpleasantness. Increased unpleasantness under N2O was linked to reduced connectivity between the right anterior insula and the anterior cingulate cortex and lateral occipital cortex. Network analyses revealed reduced modularity and a collapse of hierarchical organization, with sensorimotor connectivity redistributed toward salience and associative networks. These findings suggest that altered visual experience under N2O arises from disrupted salience integration and increased cross-network communication.