Psychopharmacology
January 5, 2018
Anna Bravermanová, Michaela Viktorinová, Filip Tylš et al.
50 citations
Psilocybin, a psychedelic that activates 5-HT2A receptors, disrupted early perceptual and higher-order cognitive processing in healthy volunteers but left pre-attentive cognition intact. In a double-blind, placebo-controlled crossover trial, 20 participants (10 men, 10 women) received 0.26 mg/kg of psilocybin orally. The drug produced robust psychedelic effects and psychotic-like symptoms, decreased the amplitude of the P300 event-related potential (a marker of attentive processing) and the N100 (an early perceptual marker), but did not affect mismatch negativity (MMN), a measure of pre-attentive processing. The disruption of P300 correlated with the intensity of the psychedelic state, which depended on psilocin serum levels. These findings suggest that 5-HT2A receptors play a role in altered information processing in psychosis and schizophrenia, particularly at early perceptual and higher-order cognitive levels.
Translational Psychiatry
October 2, 2021
Čestmír Vejmola, Filip Tylš, Václava Piorecká et al.
41 citations
Serotonergic psychedelics, including psilocin, LSD, mescaline, and DOB, all caused a time-dependent global decrease and desynchronization of EEG activity and functional disconnection in the 1–40 Hz range in freely moving rats, regardless of their chemical family. Major changes occurred in the frontal and sensorimotor cortex, with subtle spatial patterns unique to each substance. A rebound of occipital theta (4–8 Hz) activity appeared later after mescaline and LSD. Connectivity analyses revealed an overall decrease in global connectivity for both cross-spectral and phase-lagged coherence. These effects closely mirror those seen in human EEG/MEG studies, supporting the translational validity of this rodent model.
Journal of Personalized Medicine
June 19, 2022
Vojtěch Viktorin, Inga Griškova-bulanova, Aleksandras Voicikas et al.
19 citations
Psilocybin, a psychedelic compound, reduces the brain's ability to synchronize its electrical activity at 40 Hz in response to auditory clicks. In a double-blind, placebo-controlled crossover study, 20 healthy volunteers received either psilocybin (0.26 mg/kg) or placebo. Measurements taken before and after ingestion showed that psilocybin decreased the phase-locking index and amplitude of the 40 Hz auditory steady-state response, and the degree of this reduction correlated with changes in cognition and affect. These findings support the role of gamma oscillations in cognitive processing and their disruption in psychosis.
Frontiers in Neuroscience
June 22, 2023
Filip Tylš, Čestmír Vejmola, Vlastimil Koudelka et al.
9 citations
Psilocybin's psychoactivity is primarily attributed to agonism at 5-HT2A receptors, but it also binds to 5-HT2C and 5-HT1A receptors and indirectly modulates the dopaminergic system. In an animal model, psilocin (psilocybin's active metabolite) induced broadband desynchronization and disconnection in EEG, decreasing mean absolute power across 1–25 Hz and reducing global functional connectivity, particularly fronto-temporal connections. Antagonists of 5-HT1A, 5-HT2A, and 5-HT2C receptors, as well as antipsychotics haloperidol (D2 antagonist) and clozapine (mixed D2/5-HT antagonist), normalized power decreases in 1–25 Hz, but only clozapine affected 25–40 Hz decreases. The 5-HT2A antagonist reversed psilocin-induced connectivity decreases, while other drugs had no effect, indicating that multiple serotonergic and dopaminergic mechanisms contribute to these neurophysiological changes.
Biological psychiatry global open science
September 1, 2025
Čestmír Vejmola, Klára Šíchová, Kateřina Syrová et al.
4 citations
Psilocin, the active compound in psychedelic mushrooms, impairs the ability to distinguish between static and moving images in both humans and rats. In a visual discrimination task, human participants and male rats were asked to judge whether an image was static or moving. Under psilocin, both species showed significant difficulty in this task. In humans, the impairment tracked psilocin plasma levels and self-reported hallucination intensity. In rats, psilocin selectively disrupted performance in a motion-based task but not a luminance-based task, suggesting a specific effect on motion perception. Decision time was also linked to discrimination impairment. This is the first evidence that rats experience visual distortions similar to those reported by humans, offering a model for studying altered visual perception in drug-induced and psychiatric conditions.
Journal of Psychopharmacology
January 1, 2026
Petr Scholle, Štěpán Wenke, Tereza Nekovářová et al.
1 citation
Under psilocybin, healthy volunteers perceived time as moving more slowly and their temporal precision decreased, particularly for intervals longer than 2 seconds. In a double-blinded placebo-controlled study with 24 participants, the bisection point shifted rightward, indicating subjective time slowing, and the just noticeable difference increased, reflecting reduced accuracy. These changes were captured both by performance on the Temporal Bisection Task and by self-report scales. The findings suggest psilocybin disrupts cognitive functions such as working memory and attention, altering time perception through serotonergic system involvement.
bioRxiv Preprint Server
October 31, 2025
Tomas Hampejs, David Tomecek, Stanislav Jiricek et al.
preprint
Spontaneous, naturally occurring thoughts have distinct brain signatures that can be detected with combined fMRI and EEG recordings. Using machine learning on 240 samples from eight participants, internally versus externally oriented experiences were distinguished with 65.4% accuracy by fMRI and 62.5% by EEG. Externally oriented states involved greater activity in salience, auditory, and visuospatial brain networks and lower occipital alpha power, while internally oriented states showed the opposite pattern, extending prior accounts focused on the default mode network. Across modalities, alpha power correlated negatively with BOLD fluctuations in parietal and occipital regions, indicating that coordinated large-scale network dynamics and alpha oscillations track the natural alternation between inward and outward focus.
IBRO Neuroscience Reports
October 1, 2023
Čestmír Vejmola, Kateřina Syrová, Klára Šíchová et al.
GABAB receptors, which are part of the brain's inhibitory system, are modulated by accessory proteins called KCTD16. In experiments using mice lacking the KCTD16 gene, baseline pain sensitivity and nerve cell activity in the spinal cord were similar to normal mice. However, when treated with the GABAB receptor agonist baclofen, normal mice showed greater pain relief (higher thresholds for heat and touch) than mice lacking KCTD16. In a model of peripheral inflammation, KCTD16-deficient mice tended to have higher pain thresholds, and baclofen's inhibitory effect on nerve signals was reduced. The findings suggest KCTD16 may be important for pain modulation during pathological conditions when GABAB receptors are activated, but further research is needed.