TMS-EEG and resting-state EEG applied to altered states of consciousness: oscillations, complexity, and phenomenology.
Andres Ort, John W Smallridge, Simone Sarasso, Silvia Casarotto, Robin von Rotz, Andrea Casanova, Erich Seifritz, Katrin H. Preller, Giulio Tononi, Franz X. Vollenweider
iScience May 19, 2023 DOI: 10.1016/j.isci.2023.106589 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Experimental study Peer reviewed |
|---|---|
| Intervention | Psilocybin |
| Topics | Psilocybin Altered states of consciousness Philosophy of mind |
| Keywords | Medical imaging Pharmacology Neuroscience clinical neuroscience Brain science Neural studies Psychedelics hallucinogens Psychoactive compounds Neuroimaging Brain scanning |
| Citations | 47 |
| Key findings | Psilocybin produces a state of increased chaotic brain activity that is not a result of altered complexity in the underlying causal interactions between brain regions, and it evokes changes in frontal brain structures potentially linked to psychedelic experiences. |
Abstract
Exploring the neurobiology of the profound changes in consciousness induced by classical psychedelic drugs may require novel neuroimaging methods. Serotonergic psychedelic drugs such as psilocybin produce states of increased sensory-emotional awareness and arousal, accompanied by increased spontaneous electroencephalographic (EEG) signal diversity. By directly stimulating cortical tissue, the altered dynamics and propagation of the evoked EEG activity can reveal drug-induced changes in the overall brain state. We combine Transcranial Magnetic Stimulation (TMS) and EEG to reveal that psilocybin produces a state of increased chaotic brain activity which is not a result of altered complexity in the underlying causal interactions between brain regions. We also map the regional effects of psilocybin on TMS-evoked activity and identify changes in frontal brain structures that may be associated with the phenomenology of psychedelic experiences.