Subanaesthetic ketamine and altered states of consciousness in humans
British Journal of Anaesthesia April 13, 2018 Phillip E. Vlisides, Tarik Bel‐bahar, Amanda Nelson et al. 117 citations
No Summary
Amanda Nelson
Department of Anesthesiology, University of Michigan, Ann Arbor, MI, USA.
7 papers in the library · 191 citations · publishing 2018-2025
Papers
Neural Correlates of the Shamanic State of Consciousness
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.
Neurochemical and Neurophysiological Effects of Intravenous Administration of N,N-Dimethyltryptamine in Rats.
bioRxiv : the preprint server for biology February 15, 2025 Nicolas G Glynos, Emma R Huels, Amanda Nelson et al. 11 citations preprint
Intravenous DMT in rats caused dose-dependent increases in serotonin and dopamine in the medial prefrontal and somatosensory cortices, along with changes in brain wave patterns: reduced theta and low gamma power, increased delta, medium gamma, and high gamma power, and altered functional connectivity. All doses produced head twitch responses, most after the low dose. For the first time, endogenous DMT was measured in these cortical sites at levels comparable to serotonin and dopamine, suggesting a physiological role for the compound. The findings point to shared mechanisms with other psychedelics and support DMT's potential for treating psychiatric disorders.
Intravenous psilocybin induces dose-dependent changes in functional network organization in rat cortex
Translational Psychiatry March 25, 2025 Brian H Silverstein, Nicholas Kolbman, Amanda Nelson et al. 8 citations
Psilocybin alters brain network organization in rats in a dose-dependent manner. Using electroencephalography from 27 cortical sites in 12 rats, the study found that psilocybin disrupted theta-gamma coupling, increased frontal high gamma connectivity and network density, and increased posterior theta connectivity and density. Medium gamma frontoparietal connectivity and behavioral activity showed an inverted-U relationship with dose. These results suggest that high-frequency network organization, decoupled from local theta-phase, may be a key signature of psilocybin-induced altered states of consciousness.
Psilocybin induces dose-dependent changes in functional network organization in rat cortex
bioRxiv (Cold Spring Harbor Laboratory) February 12, 2024 Brian H Silverstein, Nicholas Kolbman, Amanda Nelson et al. 3 citations preprint
Psilocybin disrupts the coupling between theta and gamma brain waves in rats and reorganizes brain networks in a dose-dependent manner. Using 27 electrodes across the cortex, the study found that psilocybin increased frontal high gamma connectivity and posterior theta connectivity, as well as network density in those regions. Medium gamma frontoparietal connectivity showed a nonlinear relationship with dose. Theta-gamma phase-amplitude coupling was disrupted. These changes suggest that high-frequency network organization, decoupled from local theta-phase, may be a signature of the altered state of consciousness induced by psilocybin.
Intravenous Administration of Serotonergic Psychedelics Produce Short-lasting Changes in Sleep-Wake Behavior and High Gamma Functional Connectivity in Rats
bioRxiv (Cold Spring Harbor Laboratory) October 14, 2025 Nicholas Kolbman, Amanda Nelson, Rachel Summerfield et al. 1 citation preprint
Psilocybin and DMT, two serotonergic psychedelics, delay the onset of slow-wave sleep and REM sleep, and cause a short-lasting increase in wakefulness and decrease in slow-wave sleep in rats. Psilocybin also reduces REM sleep, decreases theta power and coherence, and increases high gamma power and coherence during wake and slow-wave sleep, as well as increasing high gamma coherence during REM sleep. DMT increases gamma coherence only during wakefulness. The enhanced high gamma functional connectivity suggests that psychedelic-induced changes in neural dynamics can occur independently of arousal states.
Neurochemical and Neurophysiological Effects of Intravenous Administration of N,N -Dimethyltryptamine in Rats
Journal of Neuroscience December 19, 2025 Nicolas G. Glynos, Emma R. Huels, Trent Groenhout et al.
In rats, intravenous DMT causes dose-dependent increases in serotonin and dopamine in the medial prefrontal and somatosensory cortices, along with distinct changes in brain wave patterns: reduced theta and low gamma power, increased delta, medium gamma, and high gamma power, and altered functional connectivity. Head twitch responses were most frequent at the lowest dose. Endogenous DMT was detected in the cortex of most animals at baseline, suggesting it may be naturally present. The work provides a detailed neurochemical and neurophysiological profile of DMT action in rats.