DMT alters cortical travelling waves
- CNRS - Université de Toulouse, France
- Imperial College London, United Kingdom
- CNRS, UMR5549, Centre de Recherche Cerveau et Cognition, Faculté de Médecine de Purpan, France
Abstract
Psychedelic drugs are potent modulators of conscious states and therefore powerful tools for investigating their neurobiology. N,N, Dimethyltryptamine (DMT) can rapidly induce an extremely immersive state of consciousness characterized by vivid and elaborate visual imagery. Here, we investigated the electrophysiological correlates of the DMT induced altered state from a pool of participants receiving DMT and (separately) placebo (saline) while instructed to keep their eyes closed. Consistent with our hypotheses, results revealed a spatio-temporal pattern of cortical activation (i.e., travelling waves) similar to that elicited by visual stimulation. Moreover, the typical top-down alpha-band rhythms of closed-eyes rest were significantly decreased, while the bottom-up forward wave was significantly increased. These results support a recent model proposing that psychedelics reduce the 'precision-weighting of priors', thus altering the balance of top-down versus bottom-up information passing. The robust hypothesis-confirming nature of these findings imply the discovery of an important mechanistic principle underpinning psychedelic-induced altered states.
Data availability
The data and the code to perform the analysis are available at : https://osf.io/wujgp/
Article and author information
Author details
Christopher Timmermann
Funding
Alex Mosley Charitable Trust
- Robin L Carhart-Harris
Ad Astra Chandaria Foundation
- Robin L Carhart-Harris
CRCNS ANR-NSF (ANR-19-NEUC-0004)
- Rufin VanRullen
Comision Nacional de Investigacion Cientifica y Tecnologica de Chile
- Christopher Timmermann
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Reviewing Editor
- Virginie van Wassenhove, CEA, DRF/I2BM, NeuroSpin; INSERM, U992, Cognitive Neuroimaging Unit, France
Ethics
Human subjects: All participants provided written informed consent, and the study was approved by the National Research Ethics (NRES) Committee London - Brent and the Health Research Authority (16/LO/0897). The study was conducted in line with the Declaration of Helsinki and the National Health Service Research Governance Framework.
Version history
- Received: June 8, 2020
- Accepted: October 11, 2020
- Accepted Manuscript published: October 12, 2020 (version 1)
- Version of Record published: October 21, 2020 (version 2)
- Version of Record updated: November 9, 2020 (version 3)
Copyright
© 2020, Alamia et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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DMT alters cortical travelling waves
eLife 9:e59784.
https://doi.org/10.7554/eLife.59784
Further reading
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- Neuroscience
Hippocampal place cells in freely moving rodents display both theta phase precession and procession, which is thought to play important roles in cognition, but the neural mechanism for producing theta phase shift remains largely unknown. Here, we show that firing rate adaptation within a continuous attractor neural network causes the neural activity bump to oscillate around the external input, resembling theta sweeps of decoded position during locomotion. These forward and backward sweeps naturally account for theta phase precession and procession of individual neurons, respectively. By tuning the adaptation strength, our model explains the difference between ‘bimodal cells’ showing interleaved phase precession and procession, and ‘unimodal cells’ in which phase precession predominates. Our model also explains the constant cycling of theta sweeps along different arms in a T-maze environment, the speed modulation of place cells’ firing frequency, and the continued phase shift after transient silencing of the hippocampus. We hope that this study will aid an understanding of the neural mechanism supporting theta phase coding in the brain.
