EEG microstate dynamics during psilocybin intoxication relate to acute experience and persisting psychological changes
Nikola Jajcay, Čestmír Vejmola, Jakub Korčák, Filip Tylš, Michaela Viktorinová, Vojtěch Viktorin, Anna Bravermanová, Renata Androvičová, Balíková, Marie,, Jiřı́ Horáček, Martin Brunovský, Jaroslav Hlinka, Tomáš Páleníček
bioRxiv (Cold Spring Harbor Laboratory) June 12, 2026 Peer reviewed DOI: 10.64898/2026.06.09.731183 via OpenAlex
Summary
Psilocybin significantly altered brain dynamics in 15 healthy volunteers during a study, increasing the number of global field power peaks and reducing microstate lifespan at peak intoxication. Despite these changes, access to canonical brain states remained largely intact. Notably, variations in brain activity correlated with both the intensity of subjective experiences during intoxication and self-reported psychological changes 28 days later, suggesting a connection between acute neural dynamics and longer-term psychological outcomes.
Study at a glance
| Design | double-blind, randomized, placebo-controlled crossover study |
|---|---|
| Sample size | 15 |
| Population | healthy volunteers |
| Key finding | Psilocybin was associated with altered temporal organization of large-scale brain dynamics while maintaining microstate coverage, with correlations to longer-term psychological outcomes. |
Abstract
Abstract Psilocybin and other serotonergic psychedelics show therapeutic promise for psychiatric disorders, yet objective neural correlates linking the acute psychedelic state to persisting psychological outcomes remain limited. Electroencephalography (EEG) microstate analysis characterizes the rapid spatiotemporal organization of large-scale brain activity, offering a millisecond-resolution window into neural dynamics. Here, we examined resting-state EEG microstates in 15 healthy volunteers who participated in a double-blind, randomized, placebo-controlled crossover study of psilocybin, using both data-driven (three-microstate) and canonical (four-microstate) analysis solutions. EEG was recorded at five time points spanning pre-drug baseline, peak intoxication, and recovery. Psilocybin significantly increased the number of global field power (GFP) peaks and reduced microstate lifespan while increasing frequency of occurrence during peak intoxication (50–100 min post-administration), consistent with accelerated transitions between brain states. Notably, microstate coverage was largely preserved, with only a transient difference at peak intoxication in the 2–20 Hz band-width, suggesting that access to the repertoire of canonical brain states is broadly maintained despite altered temporal dynamics. Critically, individual differences in microstate dynamics during peak intoxication correlated with both acute subjective experience intensity and self-reported psychological changes measured 28 days post-administration, providing exploratory evidence for a link between acute neural dynamics and longer-term experiential outcomes in healthy volunteers. These findings suggest that psilocybin is associated with altered temporal organization of large-scale brain dynamics with largely preserved microstate coverage, and identify EEG microstates as candidate neural markers for psychedelic-induced alterations in consciousness with potential relevance to therapeutic research.