Franz X. Vollenweider (born 1954) is a Swiss neuroscientist and psychiatrist best known for his research on the neuronal mechanisms of psychedelic-induced altered states of consciousness, and for exploring their relevance to the understanding and treatment of affective and psychotic disorders.
He is the director of the Consciousness Research Unit at the Center for Psychiatric Research of the Psychiatric University Hospital Zurich, the director of the Heffter Research Center Zürich for Psychedelic Research (established in 1998 in collaboration with the Heffter Research Institute USA), and the president of the Swiss Neuromatrix Foundation, which supports research in consciousness science. Until 2019, Vollenweider served as co-director of the Center for Psychiatric Research, director of the Neuropsychopharmacology and Brain Imaging Unit, and professor of Psychiatry at the University of Zurich.Franz X. Vollenweider | Department of Adult Psychiatry and Psychotherapy | UZH
Education Vollenweider was born in Lucerne, Switzerland, and attended the KSALP Gymnasium in Lucerne. He completed a Diploma in Advanced Chemistry Laboratory Technology before studying biochemistry at ETH Zurich and medicine at the University of Zurich, where he received his MD in 1986. He earned a doctorate in experimental medicine in 1987 with a thesis on comparative toxicology conducted at the Institute of Toxicology — a joint venture of ETH Zurich and the University of Zurich.Vollenweider FX (1987). Toxizitätsvergleich von Modellpestiziden (DDT, Permethrin und Fenbutatinoxid) mit hoher Fischtoxizität, jedoch relativ geringer Säugetiertoxizität an Forelle (S. gairdneri) und Maus mit besonderer Berücksichtigung der Organozinnverbindungen. WorldCat.
He subsequently conducted postdoctoral research into glutamatergic neurotransmission at the Brain Research Institute of the University of Zurich. In 1989 he joined the Research Department of Jules Angst at the Psychiatric University Hospital Zurich (PUHZ), while in parallel investigating the neuronal basis of psychedelics and related compounds using functional neuroimaging at the PET Centre of the Paul Scherrer Institute (PSI‑ETH). He completed his clinical training, including a psychoanalytic training analysis, in 1995 and obtained board certification in psychiatry and psychotherapy. In 1996, he established the Neuropsychopharmacology and Brain Imaging Research Unit at the PUHZ.Franz X. Vollenweider | Department of Adult Psychiatry and Psychotherapy | UZH
Research The Psychiatric University Hospital Zurich (Burghölzli) has been regarded as an influential center for research on psychedelic substances since the discovery of LSD in 1943 and the identification of psilocybin in the 1960s by Swiss chemist Albert Hofmann. From the early 1950s onward, psychedelic and non-pharmacologically induced altered states of consciousness were investigated from psychopathological, psychoanalytic, and psychometric perspectives.Dittrich A, von Arx S, Staub S. International study on altered states of consciousness (ISASC). Summary of the results. Germ. J. Psych. 1985; 9:319–39.Vannini C, Venturini M. Halluzinogene: Entwicklung der Forschung, 1938 bis in die Gegenwart Schwerpunkt Schweiz. VWB – Verlag für Wissenschaft und Bildung: Berlin; 1999. ISBN 3-86135-4594.
Since 1992, Vollenweider has continued and extended this multidisciplinary tradition by examining the molecular and neuronal circuit mechanisms underlying the psychological and therapeutic effects of classic psychedelics, dissociative anesthetics, and entactogens in humans. His work aims to clarify how, and to what extent, psychedelics and related compounds alter emotional, cognitive, and social processing, with the goal of informing the development of novel therapeutic approaches for neuropsychiatric disorders.Vollenweider FX. The Use of Psychotomimetics in Schizophrenia Research with Special Emphasis on the PCP/Ketamine Model Psychosis. SUCHT 1992, 38(2), 398–409.Preller KH, Vollenweider FX. Modulation of Social Cognition via Hallucinogens and "Entactogens". Front Psychiatry 2019; 10:881. Vollenweider FX, Preller KH. Psychedelic drugs: neurobiology and potential for treatment of psychiatric disorders. Nat Rev Neurosci 2020; 21(11):611–24.
Vollenweider's group integrates methods from psychology, cognitive neuroscience, and systems biology, employing advanced neuroimaging and brain-stimulation techniques such as positron emission tomography (PET), functional magnetic resonance imaging (fMRI), electroencephalography (EEG) with event-related potentials (ERP), and transcranial magnetic stimulation combined with EEG (TMS‑EEG).Vollenweider FX, Smallridge JW. Classic Psychedelic Drugs: Update on Biological Mechanisms. Pharmacopsychiatry 2022, 55, 121–138. Ort A, et al. TMS-EEG and resting-state EEG applied to altered states of consciousness: oscillations, complexity, and phenomenology. iScience 2023; 26(5):106589.
He has authored more than 200scientific papers and a monograph on the mechanisms of action of psychedelics and related psychoactive compounds.Vollenweider FX. Google Scholar profile. His early studies focused on the psychometric characterization of the subjective and pharmacological effects of psilocybin, LSD, the S‑ and R‑ketamine enantiomers, and MDMA,Studerus E, Gamma A, Vollenweider FX. Psychometric evaluation of the altered states of consciousness rating scale (OAV). PLoS One 2010; 5(8):e12412. Vollenweider FX. Brain mechanisms of hallucinogens and entactogens. Dialogues Clin Neurosci 2001; 3(4):265–79. Liechti ME, Vollenweider FX. Which neuroreceptors mediate the subjective effects of MDMA in humans? Hum Psychopharmacol 2001; 16(8):589–98. as well as on identifying neurophysiological and neuroimaging markers with potential therapeutic relevance.Vollenweider FX, Kometer M. The neurobiology of psychedelic drugs: implications for the treatment of mood disorders. Nature Reviews Neuroscience 2010, 11:642–651.
Serotonin 5-HT2A receptor and psychedelic effects His work demonstrated that the serotonin 5-HT2A receptor is a key mediator of the psychedelic experience,Vollenweider FX, et al. Psilocybin induces schizophrenia-like psychosis in humans via a serotonin-2 agonist action. NeuroReport 1998, 9:3897–3902. Preller KH, et al. The Fabric of Meaning and Subjective Effects in LSD-Induced States Depend on Serotonin 2A Receptor Activation. Curr Biol 2017, 27(3):451–457. Nutt D. Psychedelic drugs – a new era in psychiatry? Dialogues Clin Neurosci 2019, 21(2):139–147. supporting a range of perceptual, emotional, and cognitive effects in humans.
Cortico-striato-thalamo-cortical (CSTC) loop model Building on neuroimaging studies and collaborative translational psychophysiological research with Mark A. Geyer,Vollenweider FX, et al. The effects of the preferential 5-HT2A agonist psilocybin on prepulse inhibition of startle in healthy human volunteers depend on interstimulus interval. Neuropsychopharmacology 2007; 32(9):1876–87. Quednow BB, et al. Psilocybin-induced deficits in automatic and controlled inhibition are attenuated by ketanserin in healthy human volunteers. Neuropsychopharmacology 2012, 37(3):630–40. Schmid Y, et al. Acute Effects of Lysergic Acid Diethylamide in Healthy Subjects. Biol Psychiatry 2015; 78(8):544–53. Vollenweider formulated the cortico‑striato‑thalamo‑cortical (CSTC) loop model, a neurobiological framework for explaining the subjective effects of psychedelics.Vollenweider FX. Evidence for a cortical–subcortical dysbalance of sensory information processing during altered states of consciousness using PET and FDG. In: Pletscher A, Ladewig D, editors. 50 Years of LSD: Current Status and Perspectives of Hallucinogens. London: Parthenon Publishing; 1994. ISBN 1-85070-569-0.Geyer MA, Vollenweider FX. Serotonin research: contributions to understanding psychoses. Trends Pharmacol Sci 2008.
The CSTC model proposes that psychedelics disrupt thalamo‑cortical feedback circuits that regulate bottom‑up sensory gating and top‑down cognitive control, attention, and self‑awareness. According to this model, 5-HT2A receptor activation in cortical and thalamic regions reduces thalamic filtering of sensory and interoceptive information, increasing the flow of unfiltered signals to the cortex and leading to a breakdown of hierarchical control and altered cortical network integration. Neuroimaging studies have provided empirical support for the CSTC model, reporting altered thalamo‑cortical connectivity during psychedelic states and associations with specific experiential phenomena.Preller KH, et al. Changes in global and thalamic brain connectivity in LSD-induced altered states of consciousness are attributable to the 5-HT2A receptor. eLife 2018, 7:e35082. Preller KH, et al. Effective connectivity changes in LSD-induced altered states of consciousness in humans. Proc Natl Acad Sci USA 2019, 116(7):2743–2748. Müller F, et al. Increased thalamic resting-state connectivity as a core driver of LSD-induced hallucinations. Acta Psychiatr Scand 2017, 136(6):648–57. The model continues to be refined by Vollenweider's group and others.Gaddis A, et al. Psilocybin induces spatially constrained alterations in thalamic functional organization and connectivity. Neuroimage 2022, 260:119434.
Meditation and psychedelics Another line of research examines whether combining contemplative practices such as Zen or Vipassana meditation with psychedelics may yield synergistic benefits — particularly in relation to personality development and mental health.Smigielski L, et al. Psilocybin-assisted mindfulness training modulates self-consciousness and brain default mode network connectivity with lasting effects. Neuroimage 2019; 196:207–15. Smigielski L, et al. Characterization and prediction of acute and sustained response to psychedelic psilocybin in a mindfulness group retreat. Sci Rep 2019; 9(1):14914. Timmermann C, et al. A neurophenomenological approach to non-ordinary states of consciousness: hypnosis, meditation, and psychedelics. Trends Cogn Sci 2023; 27(2):139–59.
Awards and honors Vollenweider has received numerous honors, including:
Achievement Award of the Swiss Society of Psychiatry (1990) Heffter Research Institute Award (1997)Heffter Research Institute | Franz X. Vollenweider, MD Georg-Friedrich Götz Prize of the University of Zurich (2000)Götz-Prize – UZH Foundation British Association of Psychopharmacology Prize (2002)The British Association for Psychopharmacology | Annual Prizes and Awards Multiple awards from the European College of Neuropsychopharmacology (1999, 2003, 2010, 2016)
Selected publications Books Halberstadt AL, Vollenweider FX, Nichols DE (eds.) (2018). Behavioral Neurobiology of Psychedelic Drugs. Springer, Berlin, Heidelberg. . Chinese edition: Chemical Industry Press, 2021. ISBN 978-7122377692.
Journal articles Vollenweider FX, Preller KH. Psychedelic drugs: neurobiology and potential for treatment of psychiatric disorders. Nat Rev Neurosci 2020; 21(11):611–24. Vollenweider FX, Kometer M. The neurobiology of psychedelic drugs: implications for the treatment of mood disorders. Nature Reviews Neuroscience 2010, 11:642–651. von Rotz R, et al. Single-dose psilocybin-assisted therapy in major depressive disorder: A placebo-controlled, double-blind, randomised clinical trial. EClinicalMedicine 2023, 56:101809. Ort A, et al. TMS-EEG and resting-state EEG applied to altered states of consciousness: oscillations, complexity, and phenomenology. iScience 2023; 26(5):106589. Jungwirth J, et al. Psilocybin increases emotional empathy in patients with major depression. Mol Psychiatry 2025, 30:2665–2672. Stoliker D, et al. Neural mechanisms of psychedelic visual imagery. Mol Psychiatry 2025, 30:1259–1266.
Media Vollenweider has served as scientific advisor and on-screen participant in two documentary films: