Effects of External Stimulation on Psychedelic State Neurodynamics.
Pedro A M Mediano, Fernando E Rosas, Christopher Timmermann, Leor Roseman, David J Nutt, Amanda Feilding, Mendel Kaelen, Morten L Kringelbach, Adam B Barrett, Anil K Seth, Suresh Muthukumaraswamy, Daniel Bor, Robin L Carhart-Harris
ACS chemical neuroscience February 7, 2024 DOI: 10.1021/acschemneuro.3c00289 via PubMed
Summary
AI-generated from the abstractLSD increases brain entropy (neural signal diversity) across all conditions, but the effect is strongest when eyes are closed. Brain entropy changes correlate with subjective psychedelic experience ratings, except when viewing a video, possibly because external stimuli compete with LSD-induced imagery. This shows context modulates neural dynamics during psychedelic experiences, highlighting the importance of environment in psychedelic psychotherapy.
Study at a glance
| Characteristics | Experimental study Peer reviewed |
|---|---|
| Population | Participants under the effects of LSD or placebo |
| Intervention | Lysergic acid diethylamide (LSD) |
| Keywords | Complexity Consciousness Neuroscience Psychedelics Sensory processing |
| Citations | 60 |
| Key finding | LSD increases brain entropy across all conditions, with largest changes when eyes are closed, and the relationship between entropy changes and subjective experience is disrupted during video viewing. |
Abstract
Recent findings have shown that psychedelics reliably enhance brain entropy (understood as neural signal diversity), and this effect has been associated with both acute and long-term psychological outcomes, such as personality changes. These findings are particularly intriguing, given that a decrease of brain entropy is a robust indicator of loss of consciousness (e.g., from wakefulness to sleep). However, little is known about how context impacts the entropy-enhancing effect of psychedelics, which carries important implications for how it can be exploited in, for example, psychedelic psychotherapy. This article investigates how brain entropy is modulated by stimulus manipulation during a psychedelic experience by studying participants under the effects of lysergic acid diethylamide (LSD) or placebo, either with gross state changes (eyes closed vs open) or different stimuli (no stimulus vs music vs video). Results show that while brain entropy increases with LSD under all of the experimental conditions, it exhibits the largest changes when subjects have their eyes closed. Furthermore, brain entropy changes are consistently associated with subjective ratings of the psychedelic experience, but this relationship is disrupted when participants are viewing a video─potentially due to a "competition" between external stimuli and endogenous LSD-induced imagery. Taken together, our findings provide strong quantitative evidence of the role of context in modulating neural dynamics during a psychedelic experience, underlining the importance of performing psychedelic psychotherapy in a suitable environment.