Neuropsychobiology
January 1, 2011
Tomáš Páleníček, M. Fujáková, Martin Brunovský et al.
85 citations
Ketamine at behaviorally active doses induces a robust increase in EEG power spectra and coherence in rats. The drug rapidly penetrates the brain, reaching peak concentrations within 15 minutes after administration. Ketamine also produces marked hyperlocomotion and deficits in prepulse inhibition of the acoustic startle reaction, a measure of sensorimotor gating. The maximum levels of EEG change correlate with the kinetics of ketamine, and the effects are most pronounced at 10-15 minutes after administration of 30 mg/kg.
Psychopharmacology
January 1, 2013
Tomáš Páleníček, Michaela Fujáková, Martin Brunovský et al.
51 citations
The synthetic compound 2C-B produces a biphasic effect on movement in rats: initial inhibition followed by excitation, while amphetamine only causes hyperactivity. Both drugs disrupt prepulse inhibition of the acoustic startle reaction, a measure of sensory gating, but have opposite effects on the startle itself. 2C-B increases dopamine and decreases its metabolite DOPAC in the nucleus accumbens, a brain region linked to reward. Low doses of 2C-B reduce electrical brain activity and connectivity; a high dose first decreases then increases brain wave power and connectivity. Increases in theta and alpha brain waves correlate with heightened movement and dopamine levels. These results suggest 2C-B shares properties with hallucinogens, entactogens, and stimulants, and its dopamine effects may indicate psychotomimetic and addictive potential.
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.
Frontiers in Psychiatry
August 28, 2020
Veronika Andrashko, Tomáš Novák, Martin Brunovský et al.
46 citations
Concomitant benzodiazepine treatment at higher doses may attenuate the rapid antidepressant effect of a single ketamine infusion. In 47 patients with major depression who received 0.54 mg/kg ketamine as an add-on to ongoing antidepressants, 28% achieved at least a 50% reduction in depression severity within one week. Patients taking more than 8 mg of diazepam equivalent daily showed a significantly worse response on days 3 and 7 compared to those taking lower doses or none. Nonresponders had significantly higher benzodiazepine doses. The findings suggest that higher benzodiazepine doses interfere with ketamine's efficacy, with implications for clinical protocols and future research.
Psychological Medicine
December 9, 2009
Jiřı́ Horáček, Martin Brunovský, Tomáš Novák et al.
42 citations
A single dose of ketamine (0.54 mg/kg infused over 30 minutes) rapidly alters brain electrical activity in healthy volunteers, producing a decrease in prefrontal theta cordance—a QEEG measure linked to cerebral blood flow—and an increase in central region theta cordance within 10 to 30 minutes. These changes resemble those seen after one week of treatment with standard antidepressants in people who respond to them, but occur much faster. The prefrontal theta cordance reduction correlated with ketamine and norketamine blood levels at 10 minutes. The findings suggest that theta cordance reduction could serve as a marker and predictor of ketamine's rapid antidepressant effect, a hypothesis warranting testing in depressed patients.
Frontiers in Pharmacology
December 3, 2020
Daniela Dudysová, Karolína Janků, Michal Šmotek et al.
37 citations
Psilocybin, a serotonergic psychedelic with antidepressant potential, altered sleep architecture in healthy volunteers the night after administration. In a randomized, double-blinded trial, 20 healthy adults (10 women, ages 28–53) received psilocybin or placebo. Psilocybin prolonged REM sleep latency and showed a trend toward reduced total REM sleep duration, with no changes in NREM sleep or whole-night EEG power spectra. Contrary to expectations, psilocybin suppressed slow-wave activity in the first sleep cycle, providing no evidence for sleep-related neuroplasticity. The findings suggest that psilocybin's antidepressant properties may involve sleep changes, possibly through different mechanisms than those of classical antidepressants.
Clinical Neurophysiology
March 14, 2021
Torsten M. Meyer, Martin Brunovský, Jiřı́ Horáček et al.
25 citations
In patients with major depressive disorder, heart rate and heart rate variability measured before and during ketamine infusion can predict who will respond to treatment. Among 51 patients, those who responded to ketamine had a higher heart rate throughout the study, including at baseline, compared to non-responders. Ketamine infusion increased both heart rate and heart rate variability power during and after infusion. Heart rate and heart rate variability power, but not normalized frequency bands, discriminated between responders and non-responders. These findings suggest that autonomic nervous system markers may help optimize treatment selection for major depressive disorder.
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.
The International Journal of Neuropsychopharmacology
May 27, 2016
Filip Tylš, Michaela Viktorinová, Dominika Prokopcova et al.
10 citations
Among first-episode, drug-naive Han Chinese patients with schizophrenia, 24.5% had impaired glucose tolerance, compared to none of the healthy controls. Patients also had higher fasting and two-hour glucose levels, greater insulin resistance, and higher waist circumference, BMI, and triglycerides. Those with impaired glucose tolerance were older, had later schizophrenia onset, and scored higher on total and negative symptom scales, but showed no greater cognitive impairment except on an emotional intelligence measure. Abnormal glucose metabolism may be linked to clinical symptoms but not cognitive impairment in early schizophrenia.
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.
The International Journal of Neuropsychopharmacology
May 27, 2016
Tomáš Páleníček, Filip Tylš, Michaela Viktorinová et al.
6 citations
No Summary
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.
Pharmacological reports : PR
June 16, 2025
Tereza Klučková, Marek Nikolič, Filip Tylš et al.
4 citations
In healthy individuals, psilocybin produces lasting positive effects regardless of previous psychedelic experience, repeated use, setting, sex, or occupation. In a double-blind, placebo-controlled crossover study with 40 participants (20 females, mean age 38), each received two doses of psilocybin (0.26 mg/kg) at least 56 days apart. Acute effects were moderate on the Altered States of Consciousness Scales, with mostly pleasant or fluctuating experiences and only one unpleasant session; all sessions ended positively or neutrally. Long-term effects, assessed by the Persisting Effects Questionnaire, were positive across all domains with negligible negative effects. Peak experiences ending in a positive mood strongly predicted favorable long-term outcomes, while challenging experiences did not cause adverse outcomes. These findings support psilocybin's psychological safety and repeated use in clinical trials.
Journal of affective disorders
October 1, 2025
Weng-Lam Chan, Sebastian Olbrich, Xinwen Jiang et al.
3 citations
Ketamine, a drug that blocks NMDA receptors and is thought to boost neuroplasticity, increased whole-brain EEG signal complexity during infusion in patients with major depressive disorder (MDD), most of whom had treatment-resistant depression. Higher complexity at the end of infusion predicted less symptom improvement the next day, while lower occipital complexity before treatment predicted a favorable response. A logistic model using occipital complexity had moderate predictive accuracy. No changes were seen in a different complexity measure, suggesting it is not useful as a biomarker. Occipital EEG complexity may help predict which patients will benefit from ketamine therapy.
medRxiv
August 26, 2024
Tereza Klučková, Filip Tylš, Vojtěch Viktorin et al.
2 citations
preprint
In healthy volunteers, two doses of psilocybin (0.26 mg/kg) given at least 56 days apart produced moderate acute psychedelic effects that were mostly pleasant or fluctuating, with only one unpleasant experience. All sessions ended in a positive or neutral state. Psilocybin led to sustained positive effects across all domains of the Persisting Effects Questionnaire, with negligible negative effects. Contrary to expectations, dread of ego dissolution was not linked to negative long-term outcomes. Peak experiences culminating in positive mood were associated with positive lasting effects, while the type of experience (pleasant or mixed) did not correlate with the intensity or direction of the lasting effect. Results were independent of previous psychedelic experience, sex, or study setting.
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 (Cold Spring Harbor Laboratory)
June 12, 2026
Nikola Jajcay, Čestmír Vejmola, Jakub Korčák et al.
Psilocybin accelerates the temporal dynamics of large-scale brain activity while preserving access to the normal repertoire of brain states. In a double-blind, placebo-controlled crossover study of 15 healthy volunteers, EEG microstate analysis revealed that psilocybin increased the number of global field power peaks and reduced microstate lifespan while increasing their frequency of occurrence during peak intoxication (50–100 minutes after administration), indicating faster transitions between brain states. Microstate coverage was largely unchanged except for a transient difference in the 2–20 Hz bandwidth. Individual differences in these microstate dynamics correlated with both acute subjective experience intensity and self-reported psychological changes 28 days later, suggesting EEG microstates as candidate neural markers linking acute psychedelic effects to longer-term outcomes.
Therapeutic advances in psychopharmacology
January 1, 2026
Yujuan Liu, Xiaorong Liu, Sebastian Olbrich et al.
Ketamine, a rapid-acting antidepressant for treatment-resistant depression, may work by altering the brain's excitation-inhibition balance, measurable via the aperiodic exponent of EEG power spectra. In a placebo-controlled trial of 24 patients with major depressive disorder, ketamine infusion significantly reduced the aperiodic exponent across the scalp. Patients who responded to treatment had steeper pretreatment occipital aperiodic exponents, which predicted better outcomes. A meta-analysis within the study revealed substantial variability in ketamine's effect on this measure. The occipital aperiodic exponent may serve as a biomarker for predicting antidepressant response, but further large-scale studies are needed.
IBRO Neuroscience Reports
November 6, 2023
Tomáš Páleníček, Tereza Klučková, Marek Nikolič et al.
The study examined how the subjective experiences (phenomenology) induced by psilocybin, a psychedelic drug being tested as a rapid-acting antidepressant, relate to long-term changes in mood, spirituality, and relationships with self, life, and others. In healthy volunteers, positive aspects of the psychedelic experience were associated with beneficial long-term outcomes, while fearful aspects were linked to negative long-term outcomes. The findings suggest that the quality of the subjective experience during psilocybin use may influence its lasting psychological effects.