Subanaesthetic ketamine and altered states of consciousness in humans
Phillip E. Vlisides, Tarik Bel‐bahar, Amanda Nelson, K. Chilton, Ezra E. Smith, Ellen Janke, Vijay Tarnal, Paul Picton, Richard E. Harris, George A. Mashour
British Journal of Anaesthesia April 13, 2018 DOI: 10.1016/j.bja.2018.03.011 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Observational study Peer reviewed |
|---|---|
| Sample size | 15 |
| Population | Human volunteers |
| Intervention | Ketamine infusion |
| Dose | 0.5 mg kg-1 over 40 min |
| Duration | Before, during, and after 40-minute infusion |
| Topics | Ketamine Altered states of consciousness Esketamine |
| Keywords | Altered state Consciousness Cognitive science |
| Citations | 117 |
| Key findings | Ketamine-induced altered states of consciousness are accompanied by reduced alpha power in the precuneus and temporal-parietal junction. |
Abstract
BackgroundDespite its designation as a 'dissociative anaesthetic,' the dissociative and psychoactive effects of ketamine remain incompletely understood. The goal of this study was to characterise the subjective experiences and accompanying EEG changes with subanaesthetic doses of ketamine.MethodsHigh-density EEG was recorded in 15 human volunteers before, during, and after subanaesthetic ketamine infusion (0.5 mg kg-1 over 40 min), with self-reported measures of altered states of consciousness obtained after ketamine exposure. Sensor- and source-level EEG changes were analysed with a focus on spectral power and regional changes.ResultsKetamine-induced altered states were characterised predominantly by dissociative experiences such as disembodiment and ego transcendence; sensory disturbances were also common. Ketamine broadly decreased low-frequency power, with mean reductions largest at alpha (8-12 Hz) in parietal (-0.94 dB, P<0.001) and occipital (-1.8 dB, P<0.001) channel clusters. Significant decreases in alpha were identified in the precuneus and temporal-parietal junction.ConclusionsKetamine induces altered states of consciousness during periods of reduced alpha power in the precuneus and temporal-parietal junction. Modulation of these temporal-parietal loci are candidate mechanisms of the psychoactive effects of ketamine, given that this region is involved in multisensory integration, body representation, and consciousness.
Comparable studies
Other observational and cohort studies on altered states of consciousness, most cited first.
| Study | Year | Design | Participants |
|---|---|---|---|
| Neural correlates of the DMT experience assessed with multivariate EEG. 6 female, 7 male human participants | 2019 | Observational cohort | n = 13 |
| Measures of entropy and complexity in altered states of consciousness Subjects during resting wakefulness, different sleep stages, and epileptic seizures | 2017 | Observational study | |
| Altered States of Consciousness and Short-Term Psychological After-Effects Induced by the First Time Ritual Use of Ayahuasca in an Urban Context in Brazil First-time ayahuasca users in Santo Daime and União do Vegetal rituals | 2005 | Observational cohort | n = 28 |
| Quantifying arousal and awareness in altered states of consciousness using interpretable deep learning Healthy individuals during sleep, individuals under general anesthesia, and patients... | 2022 | Observational cohort | n = 71 |
| Neural and subjective effects of inhaled N,N-dimethyltryptamine in natural settings. Healthy and experienced participants | 2021 | Observational field study | n = 35 |
Citations in the library
Cited by 66
- General Anesthesia: A Probe to Explore Consciousness Frontiers in Systems Neuroscience August 14, 2019
- Cortical dynamics during psychedelic and anesthetized states induced by ketamine Neuroimage April 5, 2019
- Ketamine and Serotonergic Psychedelics: Common Mechanisms Underlying the Effects of Rapid-Acting Antidepressants The International Journal of Neuropsychopharmacology November 16, 2020
- Increased signal diversity/complexity of spontaneous EEG, but not evoked EEG responses, in ketamine-induced psychedelic state in humans. PLoS One November 23, 2020
- Characterizing brain dynamics during ketamine-induced dissociation and subsequent interactions with propofol using human intracranial neurophysiology Nature Communications March 29, 2023
and 61 more in the library
Cites 20
- Subanesthetic Effects of the Noncompetitive NMDA Antagonist, Ketamine, in Humans Archives of General Psychiatry March 1, 1994
- Neural correlates of consciousness: progress and problems Nature Reviews Neuroscience April 20, 2016
- The entropic brain: a theory of conscious states informed by neuroimaging research with psychedelic drugs Frontiers in Human Neuroscience 2014
- Psychometric Evaluation of the Altered States of Consciousness Rating Scale (OAV) PLoS One August 31, 2010
- Increased Global Functional Connectivity Correlates with LSD-Induced Ego Dissolution. Current Biology April 13, 2016
and 15 more in the library