The World Journal of Biological Psychiatry
March 1, 2010
Patrik Roser, Franz X. Vollenweider, Wolfram Kawohl
63 citations
Delta(9)-Tetrahydrocannabinol (Delta(9)-THC), the principal psychoactive constituent of the Cannabis sativa plant, and other agonists at the central cannabinoid (CB(1)) receptor may induce characteristic psychomotor effects, psychotic reactions and cognitive impairment resembling schizophrenia. These effects of Delta(9)-THC can be reduced in animal and human models of psychopathology by two...
Trends in Pharmacological Sciences
August 1, 2008
Mark A. Geyer, Franz X. Vollenweider
435 citations
The history of serotonin research is closely related to the study of hallucinogenic drugs that function as agonists at serotonin-2A receptors. The fundamental idea that psychotic states seen in psychiatric disorders such as schizophrenia might be attributable, in part, to abnormalities in serotonergic systems began with the almost simultaneous discovery of lysergic acid diethylamide (LSD),...
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...
Neuropsychopharmacology
February 14, 2007
Franz X. Vollenweider, Philipp Csomor, Bernhard Knappe et al.
194 citations
Schizophrenia patients exhibit impairments in prepulse inhibition (PPI) of the startle response. Hallucinogenic 5-HT(2A) receptor agonists are used for animal models of schizophrenia because they mimic some symptoms of schizophrenia in humans and induce PPI deficits in animals. Nevertheless, one report indicates that the 5-HT(2A) receptor agonist psilocybin increases PPI in healthy humans....
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...
Journal of Psychopharmacology
September 1, 2005
Alex Gamma, Daniel Brandeis, Ruven Brandeis et al.
36 citations
Substance abuse and associated externalizing disorders are characterized by behavioural disinhibition and low impulse control, with reduced neural inhibition postulated to be the common underlying brain mechanism. The P3 component of event-related potentials (ERPs) is a widely used neurophysiological measure thought to reflect inhibitory brain processes, but as yet has not been assessed in...
Journal of Psychopharmacology
June 27, 2005
Franz X. Vollenweider, Matthias E. Liechti, Martin P. Paulus
24 citations
Decision-making, i.e. selecting an action from a number of alternatives when the outcome is uncertain, is a complex process that is important for everyday life. 3,4-Methylenedioxymethamphetamine (MDMA), also known as 'Ecstasy', is a widely used recreational drug that is known to increase serotonin (5-HT) and, to a lesser extent, dopamine (DA) in animals. This study examined whether MDMA alters...
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...
Therapeutische Umschau
June 1, 2003
Franz X. Vollenweider, M. F. I. Vollenweider-Scherpenhuyzen
3 citations
MDMA ("Ecstasy") and its analogues such as MDE and MDA are amphetamine derivatives reported to produce an altered state with emotional overtones. Since more than ten years, ecstasy is after cannabis the most frequently used recreational drug by young adults, particularly in the so-called techno-scene. However, according to a recent survey there is an increasing trend for a revival of classic...
Neuropsychopharmacology
2003
Daniel Umbricht, Franz X. Vollenweider, Liselotte Schmid et al.
192 citations
Previously the NMDA (N-methyl-D-aspartate) receptor (NMDAR) antagonist ketamine was shown to disrupt generation of the auditory event-related potential (ERP) mismatch negativity (MMN) and the performance of an 'AX'-type continuous performance test (AX-CPT)--measures of auditory and visual context-dependent information processing--in a similar manner as observed in schizophrenia. This...
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...
Journal of Psychoactive Drugs
June 1, 2002
Franz X. Vollenweider, Matthias E. Liechti, Alex Gamma et al.
92 citations
Since the mid 1990s, MDMA has been increasingly used as a recreational drug called "Ecstasy" by young people in Europe and the United States. However, despite the widespread recreational use of Ecstasy, systematic data on the psychological and neurobiological effects of MDMA have been scant. To further our understanding of the mechanism of action of MDMA, the authors conducted several studies...
Dialogues in Clinical Neuroscience
December 31, 2001
Franz X. Vollenweider
127 citations
This review focuses on recent brain imaging and behavioral studies of sensory gating functions, which assess similarities between the effects of classic hallucinogens (eg, psilocybin), dissociative anesthetics (eg, ketamine), and entactogens (eg, 3,4-methylenedioxymethamphetamine [MDMA]) in humans. Serotonergic hallucinogens and psychotomimetic anesthetics produce overlapping psychotic...
Human Psychopharmacology Clinical and Experimental
December 1, 2001
Matthias E. Liechti, Franz X. Vollenweider
243 citations
Abstract In preclinical studies, 3,4‐methylenedioxymethamphetamine (MDMA, ‘Ecstasy’) has been shown to release serotonin (5‐HT), dopamine and norepinephrine. However, the role of these neurotransmitters and their corresponding receptor sites in mediating the subjective effects of MDMA has not yet been studied in humans. Therefore, we investigated the effects of three different neuroreceptor...
Human Brain Mapping
August 27, 2001
Edi Frei, Alex Gamma, Roberto D Pascual-Marqui et al.
175 citations
Abstract 3,4‐Methylenedioxymethamphetamine (MDMA; 'Ecstasy') is a psychostimulant drug producing heightened mood and facilitated social communication. In animal studies, MDMA effects are primarily mediated by serotonin (5‐HT), but also by dopamine (DA) and possibly noradrenaline (NA). In humans, however, the neurochemical and neurophysiological basis of acute MDMA effects remains unknown. The...
Psychopharmacology
March 5, 2001
Matthias E. Liechti, Alex Gamma, Franz X. Vollenweider
357 citations
Rationale3.4-Methylenedioxymethamphetamine (MDMA) mainly releases serotonin (5-HT) and is contained in the recreational drug Ecstasy. 5-HT is known to play an important role in mood and anxiety disorders, for which there is a female preponderance. To date, there are no systematic data on gender differences in the subjective effects of MDMA.ObjectivesThe present work analyzed the pooled data...
Journal of Clinical Psychopharmacology
February 1, 2001
Alex Gamma, Alfred Buck, Thomas Berthold et al.
84 citations
The long-term use of the serotonin-releaser and uptake-inhibitor 3,4-methylenedioxymethamphetamine (MDMA, "Ecstasy") has been associated with memory impairments and increased liability to depressive mood and anxiety attacks. It is unclear, however, whether these psychologic deviations are reflected in alterations of the underlying neurophysiologic substrate. The authors compared mood and...
Archives of General Psychiatry
December 1, 2000
Daniel Umbricht, Liselotte Schmid, Rene Koller et al.
590 citations
BACKGROUND: In patients with schizophrenia, deficient generation of mismatch negativity (MMN)-an event-related potential (ERP) indexing auditory sensory ("echoic") memory-and a selective increase of "context dependent" ("BX") errors in the "A-X" version of the Continuous Performance Test (AX-CPT) indicate an impaired ability to form and use transient memory traces. Animal and human studies...
Journal of Psychopharmacology
May 1, 2000
Matthias E. Liechti, Franz X. Vollenweider
144 citations
MDMA (3, 4-methylenedioxymethamphetamine) or ‘Ecstasy’ is a widely used recreational drug that produces a state of heightened mood but also cardiovascular and vegetative side-effects. In animals, MDMA releases serotonin and, to a lesser extent, dopamine and norepinephrine. The release of serotonin can be blocked by serotonin uptake inhibitors such as citalopram. It is unknown to what extent...
Neuropsychopharmacology
May 1, 2000
Matthias E. Liechti, Christine Baumann, Alex Gamma et al.
3,4-Methylenedioxymethamphetamine (MDMA, “Ecstasy”) is a recreational drug that has been shown to release serotonin (5-HT) and dopamine (DA) in animals. The effect of MDMA on 5-HT release can be blocked by 5-HT uptake inhibitors such as citalopram, suggesting that MDMA interacts with the 5-HT uptake site. It is unknown whether this mechanism is also responsible for the psychological effects of...