Psilocybin acutely reduces low-frequency BOLD power and frequency-specific connectivity
Anders S. Olsen, Kristian Larsen, Drummond E. Mcculloch, Melanie Ganz, Martin K Madsen, Brice Ozenne, Gitte M. Knudsen, Naveed Ur Rehman, Patrick M. Fisher
bioRxiv April 13, 2026 preprint DOI: 10.64898/2026.04.09.717379 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Observational cohort |
|---|---|
| Sample size | 28 |
| Population | Healthy volunteers |
| Intervention | Psilocybin |
| Dose | 0.2 – 0.3 mg/kg |
| Topics | Psilocybin |
| Key findings | Psilocybin produced a selective reduction in low-frequency spectral power (0.01–0.06 Hz) and an increase in spectral entropy, with strongest effects in transmodal networks. |
Abstract
Abstract Psilocybin and other serotonergic drugs acutely alter human brain function and large-scale connectivity as measured with BOLD fMRI, but whether these effects are frequency-specific remains unknown. We applied multitaper spectral and cross-spectral analyses to resting-state fMRI data from 28 healthy volunteers scanned multiple times acutely following oral psilocybin administration (0.2 – 0.3 mg/kg), together with plasma psilocin measurements, to estimate psilocin associations with temporal frequency-specific activity and connectivity. Psilocybin produced a selective reduction in low-frequency spectral power (0.01 – 0.06 Hz ) and an increase in spectral entropy, with the strongest effects in transmodal networks. We also observed a reduction in low-frequency connectivity energy explained by the unimodal/transmodal axis. These findings demonstrate that psilocin induces spatially distributed, frequency-dependent alterations, suggesting that broadband fMRI analyses may obscure low-frequency dynamics. Frequency-resolved approaches may offer greater sensitivity for characterizing psychedelic effects on brain activity.