Journal of Psychopharmacology
September 20, 2010
Erich Studerus, Michael Kometer, Felix Hasler et al.
529 citations
Psilocybin and related hallucinogenic compounds are increasingly used in human research. However, due to limited information about potential subjective side effects, the controlled medical use of these compounds has remained controversial. We therefore analysed acute, short- and long-term subjective effects of psilocybin in healthy humans by pooling raw data from eight double-blind...
Journal of Vision
March 19, 2010
Olivia Carter, John D. Pettigrew, Felix Hasler et al.
3 citations
Binocular rivalry refers to the fluctuations in visual awareness/suppression that occur when different images are simultaneously presented to each eye. To explore the role of serotonin (5-HT) in binocular rivalry, this study investigated the affects of the hallucinogenic 5-HT1A&2A receptor agonist psilocybin (the active compound in “magic mushrooms”), alone and after pretreatment with the...
Journal of Psychopharmacology
July 17, 2008
Felix Hasler, Erich Studerus, Karl‐johan Lindner et al.
53 citations
Serotonin (5-HT) release is the primary pharmacological mechanism of 3,4-methylenedioxymethamphetamine (MDMA, ‘ecstasy’) action in the primate brain. Dopamine release and direct stimulation of dopamine D2 and serotonin 5-HT 2A receptors also contributes to the overall action of MDMA. The role of 5-HT 1A receptors in the human psychopharmacology of MDMA, however, has not yet been elucidated. In...
Neuroscience Letters
February 13, 2008
Jiřı́ Wackermann, Marc Wittmann, Felix Hasler et al.
95 citations
Action of a hallucinogenic substance, psilocybin, on internal time representation was investigated in two double-blind, placebo-controlled studies: Experiment 1 with 12 subjects and graded doses, and Experiment 2 with 9 subjects and a very low dose. The task consisted in repeated reproductions of time intervals in the range from 1.5 to 5s. The effects were assessed by parameter kappa of the...
Psychopharmacology
September 13, 2007
Olivia Carter, Felix Hasler, John D. Pettigrew et al.
150 citations
RationaleBinocular rivalry occurs when different images are simultaneously presented to each eye. During continual viewing of this stimulus, the observer will experience repeated switches between visual awareness of the two images. Previous studies have suggested that a slow rate of perceptual switching may be associated with clinical and drug-induced psychosis.ObjectivesThe objective of the...
Journal of Psychopharmacology
May 20, 2006
Marc Wittmann, Olivia Carter, Felix Hasler et al.
245 citations
Hallucinogenic psilocybin is known to alter the subjective experience of time. However, there is no study that systematically investigated objective measures of time perception under psilocybin. Therefore, we studied dose-dependent effects of the serotonin (5-HT) 2A/1A receptor agonist psilocybin (4-phosphoryloxy-N, N-dimethyltryptamine) on temporal processing, employing tasks of temporal...
Journal of Cognitive Neuroscience
October 1, 2005
Olivia Carter, David C. Burr, John D. Pettigrew et al.
236 citations
Abstract Increasing evidence suggests a link between attention, working memory, serotonin (5-HT), and prefrontal cortex activity. In an attempt to tease out the relationship between these elements, this study tested the effects of the hallucinogenic mixed 5-HT1A/2A receptor agonist psilocybin alone and after pretreatment with the 5-HT2A antagonist ketanserin. Eight healthy human volunteers were...
Neuropsychopharmacology
January 26, 2005
Olivia Carter, John D. Pettigrew, Felix Hasler et al.
122 citations
Binocular rivalry occurs when different images are presented simultaneously to corresponding points within the left and right eyes. Under these conditions, the observer's perception will alternate between the two perceptual alternatives. Motivated by the reported link between the rate of perceptual alternations, symptoms of psychosis and an incidental observation that the rhythmicity of...
Neuroreport
August 1, 2004
Olivia Carter, John D. Pettigrew, David C. Burr et al.
83 citations
The hallucinogenic serotonin(1A&2A) agonist psilocybin is known for its ability to induce illusions of motion in otherwise stationary objects or textured surfaces. This study investigated the effect of psilocybin on local and global motion processing in nine human volunteers. Using a forced choice direction of motion discrimination task we show that psilocybin selectively impairs coherence...
Psychopharmacology
March 1, 2004
Felix Hasler, Ulrike Grimberg, Marco A. Benz et al.
458 citations
RationaleSerotonin (5-Hydroxytryptamine, 5-HT) receptors play an important role in perception, affect regulation and attention. Pharmacological challenge with the 5-HT(2A) agonist psilocybin (PY) is useful in studying the neurobiological basis of cognition and consciousness.ObjectiveInvestigation of dose-dependent effects of PY on psycho(patho)logical and physiological parameters.MethodsEight...
Journal of Pharmaceutical and Biomedical Analysis
August 26, 2002
Felix Hasler, Daniel Bourquin, Rudolf Brenneisen et al.
100 citations
In a clinical study eight volunteers received psilocybin (PY) in psychoactive oral doses of 212+/-25 microg/kg body weight. To investigate the elimination kinetics of psilocin (PI), the first metabolite of PY, urine was collected for 24 h and PI concentrations were determined by high-performance liquid chromatography with column switching and electrochemical detection (HPLC-ECD). Sample workup...
Pharmaceutica Acta Helvetiae
June 1, 1997
Felix Hasler, Daniel Bourquin, Rudolf Brenneisen et al.
231 citations
In order to investigate the pharmacokinetic properties of psilocybin (PY), the main psychoactive compound of Psilocybe mushrooms, high performance liquid chromatographic procedures with column-switching coupled with electrochemical detection (HPLC-ECD) for reliable quantitative determination of the PY metabolites psilocin (PI) and 4-hydroxyindole-3-acetic acid (4HIAA) in human plasma were...