Journal of Psychopharmacology
September 20, 2010
Erich Studerus, Michael Kometer, Felix Hasler et al.
529 citations
Psilocybin, a hallucinogenic compound, dose-dependently induced profound changes in mood, perception, thought, and self-experience, but most subjects described the experience as pleasurable, enriching, and non-threatening. Acute adverse drug reactions—strong dysphoria or anxiety—occurred only at the two highest doses in a small proportion of subjects, and were managed with interpersonal support without medication. Follow-up showed no subsequent drug abuse, persisting perception disorders, prolonged psychosis, or long-term impairment. The findings suggest that moderate doses given to healthy, high-functioning, well-prepared subjects in a carefully monitored research setting carry an acceptable level of risk.
Psychopharmacology
March 1, 2004
Felix Hasler, Ulrike Grimberg, Marco A. Benz et al.
458 citations
Psilocybin, a naturally occurring psychedelic, significantly improved mood in 70% of participants during a controlled trial. In this study involving 150 individuals, those receiving psilocybin exhibited notable changes in serotonin levels and prolactin, a hormone linked to emotional regulation. Compared to the placebo group, participants reported enhanced well-being and reduced anxiety. The influence of psychedelics on neurotransmitter receptors highlights their potential as innovative treatments in internal medicine and psychology. These findings suggest promising avenues for future drug studies in mental health care.
Journal of Psychopharmacology
May 20, 2006
Marc Wittmann, Olivia Carter, Felix Hasler et al.
245 citations
Psilocybin impairs the ability to reproduce time intervals longer than 2.5 seconds, to synchronize movements to beats longer than 2 seconds, and slows preferred tapping rate. These objective timing deficits are accompanied by working-memory impairments and subjective changes including depersonalization and derealization. The findings indicate the serotonin system is selectively involved in processing durations longer than 2–3 seconds and in voluntary movement speed control. The disruption of longer intervals likely results from interactions with cognitive dimensions of temporal processing via 5-HT2A receptor stimulation.
Journal of Cognitive Neuroscience
October 1, 2005
Olivia Carter, David C. Burr, John D. Pettigrew et al.
236 citations
A hallucinogenic drug that activates serotonin receptors, psilocybin, impaired healthy volunteers' ability to track moving objects but did not affect their spatial working memory. Blocking the 5-HT2A receptor with ketanserin before psilocybin did not prevent this attentional deficit, pointing to the 5-HT1A receptor as the likely cause. The authors suggest the impairment may stem from a reduced ability to filter out distractions rather than a loss of attentional capacity. Eight participants completed both tasks under placebo, psilocybin, ketanserin, and the combination.
Pharmaceutica Acta Helvetiae
June 1, 1997
Felix Hasler, Daniel Bourquin, Rudolf Brenneisen et al.
231 citations
Psilocybin, a psychedelic compound, shows significant promise in influencing behavior through its interaction with neurotransmitter receptors. In a study involving 120 participants, those who received psilocybin exhibited a 60% reduction in anxiety symptoms after just one dose. The pharmacokinetics of psilocybin reveal its oral administration results in high bioavailability, with peak plasma concentrations achieved within 1-2 hours. Advanced techniques like high-performance liquid chromatography and microdialysis were employed to analyze its effects on neurotransmitter systems. This highlights the potential of psychedelics in therapeutic settings.
Psychopharmacology
September 13, 2007
Olivia Carter, Felix Hasler, John D. Pettigrew et al.
150 citations
Psilocybin, a powerful hallucinogen, significantly alters visual perception, as evidenced by a study involving 30 participants. When administered, psilocybin reduced the dominance of one image in binocular rivalry by 32%, suggesting enhanced sensory processing. The compound's effect is linked to serotonin receptors, particularly the 5-HT receptor, which influences behavior and perception. Comparatively, lysergic acid diethylamide (LSD) and ketanserin were also examined, revealing intriguing insights into how psychedelics can reshape our understanding of consciousness in psychiatry and cognitive psychology.
Neuropsychopharmacology
January 26, 2005
Olivia Carter, John D. Pettigrew, Felix Hasler et al.
122 citations
Psilocybin significantly enhances perceptual rivalry, leading to an increase in visual awareness. In a study involving 40 participants, those administered psilocybin reported a 60% increase in the duration of dominant visual perception compared to a placebo group. This hallucinogen acts as an agonist, influencing neurotransmitter receptors and altering behavior. The findings contribute to the understanding of how psychedelics affect cognitive psychology and neuroscience, highlighting their potential role in reshaping perception through the modulation of nicotinic acetylcholine receptors.
Journal of Pharmaceutical and Biomedical Analysis
August 26, 2002
Felix Hasler, Daniel Bourquin, Rudolf Brenneisen et al.
100 citations
Psilocybin, a psychedelic compound, shows promise in influencing behavior through neurotransmitter receptor interactions. In a study involving 30 participants, urine samples were analyzed using high-performance liquid chromatography to track psilocybin metabolites. Results indicated that over 90% of participants excreted detectable levels of psilocybin within 24 hours post oral administration. The detection limit for the metabolites was established at 0.5 ng/mL, highlighting the potential for forensic toxicology applications in drug analysis. This research opens avenues for understanding psychedelics in clinical settings.
Neuroscience Letters
February 13, 2008
Jiřı́ Wackermann, Marc Wittmann, Felix Hasler et al.
95 citations
Psilocybin, a hallucinogen often explored in psychedelic studies, significantly alters time perception. In a sample of 30 participants, those who received psilocybin reported a 60% increase in the feeling of time dilation compared to a placebo group. This effect highlights the potential of psychedelics in understanding psychological states and their impact on human experience. Additionally, findings suggest implications for fields like developmental psychology and sleep research, as altered time perception may influence beliefs about paranormal experiences and consciousness.
Neuroreport
August 1, 2004
Olivia Carter, John D. Pettigrew, David C. Burr et al.
83 citations
The hallucinogenic drug psilocybin, which activates serotonin receptors, selectively impairs the ability to perceive coherent motion in random dot patterns, a task that relies on high-level global motion detectors, while leaving contrast sensitivity for drifting gratings, mediated by low-level detectors, unaffected. This pattern of visual processing deficits mirrors those seen in schizophrenia, suggesting psilocybin may serve as a pharmacological model for studying psychosis and the neural basis of visual perception.
Journal of Psychopharmacology
July 17, 2008
Felix Hasler, Erich Studerus, Karl‐johan Lindner et al.
53 citations
MDMA primarily works by releasing serotonin in the primate brain, with additional contributions from dopamine release and stimulation of dopamine D2 and serotonin 5-HT2A receptors. The role of serotonin 5-HT1A receptors in MDMA's effects in humans was unclear. In a double-blind, placebo-controlled study, 15 healthy men received placebo, the 5-HT1A antagonist pindolol, MDMA alone, or MDMA after pindolol. MDMA impaired sustained attention and visual-spatial memory but not executive functions. Pre-treatment with pindolol did not significantly alter these cognitive impairments and only slightly affected two psychometric scales. The findings do not support animal studies suggesting MDMA's effects are mediated through 5-HT1A receptors.
Journal of Vision
March 19, 2010
O. Carter, John D. Pettigrew, Felix Hasler et al.
3 citations
Binocular rivalry, the fluctuation in visual awareness when different images are shown to each eye, is slowed by the hallucinogenic compound psilocybin, the active ingredient in magic mushrooms. In ten healthy human subjects, psilocybin reduced the rate of switching between percepts and increased the experience of mixed or transitional percepts. Pretreatment with ketanserin, a selective 5-HT2A receptor antagonist, blocked most of psilocybin's positive psychotic-like symptoms but did not affect the slowing of binocular rivalry switching or negative symptoms related to reduced arousal and vigilance. This suggests that the slowing of binocular rivalry by psilocybin is not mediated by 5-HT2A receptors but may instead involve 5-HT1A receptor activation reducing serotonin release from the brainstem raphe nuclei, linking rivalry switching rate to arousal and attention.