A dominant frontoparietal beta oscillatory brain state in the days after psilocybin and 5-MeO-DMT
Chloe L. West, Bradley Baker, Annabel Duran, Samen Nadeem, Vince D Calhoun, Neil Van Leeuwen, Jordan P. Hamm
bioRxiv (Cold Spring Harbor Laboratory) August 27, 2026 preprint DOI: 10.64898/2026.08.23.746502 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Observational cohort |
|---|---|
| Sample size | 42 |
| Population | Individuals who used psilocybin/LSD or 5-MeO-DMT within the prior three weeks and age- and sex-matched controls |
| Topics | 5-MeO-DMT DMT Psilocybin |
| Key findings | A right frontoparietal beta synchrony state was dominant after both typical and atypical psychedelic use, correlating with days since use. A globally distributed theta state was prominent after typical psychedelics but less frequent after atypical use. Neural entropy was not altered in recent users. |
Abstract
Abstract Background Serotonergic psychedelics show promise for treating psychiatric disorders, with symptom improvements lasting for weeks after a single dose. Clarifying the neural basis of these effects would benefit from an identification of empirical biomarkers of such lasting shifts in brain function. Resting state EEG offers a rapid (<5 minute), low-cost window into functional brain networks. However, connectivity is not static, but cycles between recurring semi-stable patterns that vary across frequency bands. Here we employed a dynamic function connectivity (dFC) framework to identify frequency-specific connectivity states and examine how they change in the weeks following psychedelic use.
Methods: We collected resting-state EEG from individuals who had used one of two serotonergic psychedelic subclasses within the prior three weeks, psilocybin/LSD (typical; n=14) or 5-MeO-DMT (atypical; n=12), and age- and sex-matched controls (n=16). Frequency-band-specific spatial connectivity states (phase-lag index) were estimated across the full sample (5 per band). Groups were compared on proportion and dwell-time (per state) and state-to-state transitions.
Results: A right frontoparietally-distributed beta synchrony state was dominant after both typical and atypical psychedelics use (proportion/dwell-time). This effect correlated with the number of days since using psychedelics. A globally-distributed theta-band state was prominent in recent users of typical psychedelics but occurred less often in atypical users. In contrast, neural entropy (Lempel-Ziv complexity; known to increase acutely during psychedelic dosing) was not altered in recent users of either subclass.
Conclusion: These results reveal a beta-band signature of altered neural dynamics in the week following a psychedelic dose, consistent with a relaxation of brain network hierarchy after psychedelics.