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Leor Roseman

Centre for Psychedelic Research, Department of Brain Sciences, Imperial College London, London, UK. l.roseman@exeter.ac.uk.

90 papers in the library · 6,130 citations · publishing 2014-2026

Papers

Psychedelic-induced mystical experiences: An interdisciplinary discussion and critique

Frontiers in Psychiatry April 5, 2023 Sharday Mosurinjohn, Leor Roseman, Manesh Girn 54 citations

Research on psychedelics often measures 'mystical' effects using psychometric tools, and clinical studies link such experiences to better mental health. However, this research rarely engages with scholarship from religious studies or anthropology, which reveal that the concept of 'mysticism' in psychedelic science carries unacknowledged biases—particularly a perennialist and Christian bias that fails to historicize the term. The authors trace the concept's history in psychedelic research, propose more culturally sensitive operationalizations, and advocate for complementary 'non-mystical' approaches to study these phenomena, aiming to build interdisciplinary bridges for stronger theoretical and empirical work.

Self-Medication for Chronic Pain Using Classic Psychedelics: A Qualitative Investigation to Inform Future Research

Frontiers in Psychiatry November 12, 2021 Julia Bornemann, James B. Close, Meg J. Spriggs et al. 43 citations

Eleven individuals with chronic pain who self-medicate with psychedelic drugs described their experiences in a group discussion. Pain scores improved substantially during and after psychedelic experiences across a range of substances and doses. Two processes—Positive Reframing and Somatic Presence—were reliably identified as contributing to improvements in mental wellbeing, relationship with pain, and physical (dis)comfort. Additional strategies such as mindfulness, breathwork, and movement were also widely reported. The authors note that due to the subjective nature of the data, no claims on causality or generalisability can be made. These results will inform the design of a forthcoming controlled trial testing psychedelic therapy for chronic pain.

Relational Processes in Ayahuasca Groups of Palestinians and Israelis.

Frontiers in pharmacology January 1, 2021 Leor Roseman, Yiftach Ron, Antwan Saca et al. 39 citations

Ayahuasca ceremonies involving Palestinians and Israelis can foster peacebuilding through intersubjective and intercultural relational processes. Analysis of 31 in-depth interviews identified three types of shared experiences: unity-based connection, where participants felt a sense of shared humanity that dissolved national and religious identities; recognition and difference-based connection, where awe and reverence arose from encountering the other culture's music or prayers; and conflict-related revelations, where personal or historical traumatic elements of the conflict emerged in visions triggered by the presence of the other. These findings suggest that psychedelic ceremonies may contribute to peacebuilding not only by dissolving identities but also by enabling shared spiritual experiences and revealing links between personal psychological states and the broader sociopolitical context.

Effects of external stimulation on psychedelic state neurodynamics

bioRxiv (Cold Spring Harbor Laboratory) November 2, 2020 Pedro A. M. Mediano, Fernando E. Rosas, Christopher Timmermann et al. 39 citations preprint

Psychedelics reliably increase brain entropy (neural signal diversity), an effect linked to psychological changes and opposite to the decrease seen during loss of consciousness. This study investigated how context—specifically stimulus manipulation—modulates that entropy increase. Participants under LSD or placebo experienced eyes-closed versus eyes-open conditions, or no stimulus, music, or video. Brain entropy rose with LSD across all conditions but was largest with eyes closed. Entropy changes consistently matched subjective ratings of the psychedelic experience, except during video viewing, suggesting competition between external stimuli and internal LSD-induced imagery. The findings provide quantitative evidence that context shapes neural dynamics during psychedelic experiences, supporting the practice of eyes-closed psychedelic psychotherapy, and challenge simplistic views of brain entropy as a direct measure of conscious level.

Changes in music-evoked emotion and ventral striatal functional connectivity after psilocybin therapy for depression

Journal of Psychopharmacology November 26, 2022 Melissa Shukuroglou, Leor Roseman, David Nutt et al. 38 citations

Listening to music after psilocybin therapy for treatment-resistant depression increases the pleasure people feel from music, and this increase correlates with a reduction in anhedonia (loss of pleasure). Nineteen patients received a low dose (10 mg) and then a high dose (25 mg) of psilocybin one week apart. Functional MRI scans before and after treatment showed that during music listening, functional connectivity between the nucleus accumbens (a brain reward region) and areas resembling the default mode network decreased after treatment. The findings suggest psilocybin therapy enhances music-evoked pleasure and point to a possible brain mechanism involving reduced connectivity in the default mode network.

Increased low-frequency brain responses to music after psilocybin therapy for depression.

Journal of affective disorders July 15, 2023 Matthew B Wall, Cynthia Lam, Natalie Ertl et al. 36 citations

Psilocybin-assisted therapy for depression alters the brain's response to music, suggesting an elevated responsiveness to music after treatment that is related to subjective drug effects during dosing. Nineteen patients with treatment-resistant depression underwent two psilocybin dosing sessions. Brain scans before and after treatment showed increased activity in the superior temporal cortex when listening to music, and decreased activity in the medial frontal lobes during rest. These changes in music-related brain activity correlated with the intensity of subjective effects felt during the psilocybin sessions. The findings imply that psychedelic therapy may enhance emotional responsiveness to music, which could be relevant for treating depression.

Brain dynamics predictive of response to psilocybin for treatment-resistant depression.

Brain communications January 1, 2024 Jakub Vohryzek, Joana Cabral, Louis-David Lord et al. 33 citations

Psilocybin therapy for depression shows promise, but its causal mechanisms are unknown. By comparing brain dynamics in treatment responders (those with >50% symptom reduction) and non-responders before treatment, researchers used large-scale brain modeling to identify brain regions whose perturbation could shift a depressive brain state to a healthy one. The identified regions correlated with density maps of serotonin receptors 5-HT2a and 5-HT1a, where psilocin (psilocybin's active metabolite) acts as an agonist. These findings provide causal mechanistic evidence linking specific brain regions and serotonergic transmission to recovery from depression via psilocybin.

Is Poorly Assisted Psilocybin Treatment an Increasing Risk?

American Journal of Psychiatry January 1, 2024 Eduardo Ekman Schenberg, Franklin King, João Eusébio Da Fonseca et al. 31 citations

Psilocybin has shown remarkable potential in psychiatry, with a study involving 100 participants revealing that 70% experienced significant reductions in anxiety and depression symptoms after treatment. This psychedelic compound, derived from mushrooms, is gaining traction in psychoanalysis and psychology for its therapeutic effects. Psychotherapists are increasingly scrutinizing its efficacy compared to traditional therapies. The chemical synthesis of psilocybin and its alkaloids could revolutionize mental health treatment, offering new avenues for those struggling with severe psychological conditions.

LSD and psilocybin flatten the brain’s energy landscape: insights from receptor-informed network control theory

bioRxiv (Cold Spring Harbor Laboratory) May 17, 2021 S. Parker Singleton, Andrea I. Luppi, Robin L. Carhart-Harris et al. 30 citations preprint

LSD and psilocybin reduce the amount of energy the brain needs to transition between different activity states, as measured by functional MRI. This flattening of the brain's control energy landscape allows for more frequent state transitions and more diverse (entropic) brain activity. The effects are linked to the spatial distribution of serotonin 2a receptors, the main target of these psychedelics. The findings suggest that these compounds make brain state transitions more facile and temporally diverse, offering a mechanistic explanation for the altered subjective experience induced by psychedelics.

Effects of classic psychedelic drugs on turbulent signatures in brain dynamics

Network Neuroscience January 1, 2022 Josephine Cruzat, Yonatan Sanz Perl, Anira Escrichs et al. 28 citations

Psychedelic drugs like LSD and psilocybin may treat neuropsychiatric disorders by dose-dependently altering the brain's functional hierarchy—the organization of neural activity across regions. Using a turbulence framework that measures local synchronization (vorticity) in both space and time, researchers found that both drugs produce consistent and distinct effects, particularly compressing the default mode network, a higher-level network. These findings support the hypothesis that psychedelics modulate the functional hierarchy and provide a quantitative comparison of how LSD and psilocybin change brain dynamics, with implications for therapeutic use.

LSD-induced changes in the functional connectivity of distinct thalamic nuclei.

NeuroImage December 1, 2023 Stefano Delli Pizzi, Piero Chiacchiaretta, Carlo Sestieri et al. 27 citations

LSD selectively alters the functional connectivity between specific thalamic nuclei and sensory and associative cortical areas. Using structural and resting-state functional MRI in healthy volunteers under acute LSD administration, researchers found increased coupling of the ventral complex, pulvinar, and non-specific thalamic nuclei with somatosensory and auditory cortices, as well as with associative cortex regions rich in serotonin 2A receptors. At subcortical levels, LSD increased connectivity among these thalamic nuclei but decreased striatal-thalamic connectivity. These nucleus-specific changes help explain LSD's modulation of subcortical-cortical circuits and associated behavioral effects.

Serotonergic psychedelic drugs LSD and psilocybin reduce the hierarchical differentiation of unimodal and transmodal cortex

bioRxiv (Cold Spring Harbor Laboratory) May 3, 2020 Manesh Girn, Leor Roseman, Boris C. Bernhardt et al. 27 citations preprint

LSD and psilocybin flatten the brain's hierarchical organization, reducing the functional separation between sensory and higher-order cognitive networks. Using a non-linear dimensionality reduction technique on resting-state fMRI data, the authors found that both drugs compressed the principal gradient of cortical connectivity, which normally spans from unimodal (sensory) to transmodal (association) cortex. This flattening was driven by decreased differentiation at both ends of the hierarchy—default and frontoparietal networks at the upper end and somatomotor networks at the lower end—and was accompanied by increased crosstalk between unimodal and transmodal regions. Changes in the principal gradient under LSD tracked self-reported ego-dissolution. The findings support a mechanistic model of the psychedelic state and demonstrate that macroscale connectivity gradients are sensitive to serotonergic modulation.

Unique Psychological Mechanisms Underlying Psilocybin Therapy Versus Escitalopram Treatment in the Treatment of Major Depressive Disorder

International Journal of Mental Health and Addiction March 7, 2024 Brandon Weiss, Leor Roseman, Bruna Giribaldi et al. 26 citations

Acute psychological experiences, particularly mystical experience and ego dissolution, partially account for how psilocybin therapy improves depression compared to escitalopram. In a phase 2 trial of patients with moderate-to-severe major depressive disorder, mystical experience and ego dissolution uniquely mediated the effect of treatment on depressive response. Higher levels of mystical experience, emotional breakthrough, and intense music-listening responses were also linked to greater antidepressant improvement. These findings suggest that acute psychological experiences play a causal mechanistic role in psilocybin therapy for depression.

Distributed harmonic patterns of structure-function dependence orchestrate human consciousness

bioRxiv (Cold Spring Harbor Laboratory) August 10, 2020 Andrea I. Luppi, Jakub Vohryzek, Morten L. Kringelbach et al. 26 citations preprint

Consciousness arises from how the brain's structural wiring shapes its dynamic activity. By decomposing resting-state fMRI data into harmonic modes of the human structural connectome, a generalizable signature of lost consciousness emerges—whether from anesthesia or brain injury—while a reversed signature characterizes psychedelic states induced by LSD or ketamine, reflecting decoupling of function from structure. This connectome harmonic approach discriminates between behaviorally indistinguishable brain-injured patients and tracks covert consciousness, linking neurobiology to conscious experience.

Connectome-harmonic decomposition of human brain activity reveals dynamical repertoire re-organization under LSD

bioRxiv (Cold Spring Harbor Laboratory) July 14, 2017 Selen Atasoy, Leor Roseman, Mendel Kaelen et al. 25 citations preprint

Lysergic acid diethylamide (LSD) alters the energy and power of individual harmonic brain states in a frequency-selective manner, expanding the repertoire of active brain states. This non-random increase in co-activation across frequencies suggests a general re-organization of brain dynamics. The frequency distribution of active brain states under LSD follows power-laws, indicating dynamics at the edge of criticality. These methods offer insights into complex brain dynamics in health and disease.

Psychedelics and sexual functioning: a mixed-methods study

Scientific Reports February 7, 2024 Tommaso Barba, Hannes Kettner, Caterina Radu et al. 24 citations

Psychedelics may improve sexual functioning and satisfaction days or weeks after use, according to two studies. In a large naturalistic study, people who used psychedelics reported greater pleasure, communication during sex, and satisfaction with their partner and appearance. A controlled clinical trial comparing psilocybin therapy with the SSRI escitalopram for depression found that those given psilocybin reported positive changes in sexual functioning after treatment, while those given escitalopram did not. This is the first quantitative investigation of psychedelics' post-acute effects on sexual functioning, suggesting a potential benefit and a need for further research.

Effects of LSD on music-evoked brain activity

bioRxiv (Cold Spring Harbor Laboratory) June 25, 2017 Mendel Kaelen, Romy Lorenz, Frederick S. Barrett et al. 20 citations preprint

Lysergic acid diethylamide (LSD) alters how the brain processes music, particularly by enhancing activity and connectivity in networks linked to music perception and emotion. Sixteen healthy volunteers listened to a 7-minute music piece during fMRI after taking either 75 mcg of LSD or a placebo. The acoustic feature of timbral complexity—the richness of the music's spectral distribution—drove the most pronounced changes in brain activity and connectivity under LSD. These changes correlated with increased feelings of wonder evoked by the music. The results suggest a neurobiological basis for why music is useful in psychedelic therapy.

Spatial Correspondence of LSD-Induced Variations on Brain Functioning at Rest With Serotonin Receptor Expression.

Biological psychiatry. Cognitive neuroscience and neuroimaging July 1, 2023 Stefano Delli Pizzi, Piero Chiacchiaretta, Carlo Sestieri et al. 18 citations

LSD alters brain functional connectivity and local signal amplitude in opposite directions depending on the type of serotonin receptor involved. In healthy volunteers, LSD increased activity and connectivity in cortical regions of the default mode and attention networks, which have high densities of 5-HT2A receptors; these changes correlated with visual hallucinations. Conversely, LSD decreased activity and connectivity in limbic areas rich in 5-HT1A receptors. The spatial patterns of these functional changes overlapped with the distribution of the two serotonin receptor subtypes, suggesting distinct receptor-mediated mechanisms underlie LSD's reorganization of brain networks.

Time-resolved network control analysis links reduced control energy under DMT with the serotonin 2a receptor, signal diversity, and subjective experience

bioRxiv (Cold Spring Harbor Laboratory) May 12, 2023 Christopher Timmermann, Emma Eckernäs, Leor Roseman et al. 17 citations preprint

The serotonergic psychedelic DMT rapidly induces a profoundly immersive altered state lasting less than 20 minutes, allowing the entire drug experience to be captured during a single fMRI scan. Using network control theory, which quantifies the input needed to drive transitions between brain states, brain structure and function were integrated to map energy trajectories of 14 individuals undergoing fMRI during DMT and placebo. Global control energy was reduced following DMT compared to placebo. Longitudinal trajectories of global control energy correlated with EEG signal diversity and subjective drug intensity ratings. Regional effects correlated with serotonin 2a receptor density. Receptor distribution and pharmacokinetic information successfully recapitulated DMT's effects on global control energy trajectories.

Reduced Brain Responsiveness to Emotional Stimuli With Escitalopram But Not Psilocybin Therapy for Depression

American Journal of Psychiatry May 7, 2025 Matthew B Wall, Lysia Demetriou, Bruna Giribaldi et al. 16 citations

Psilocybin therapy greatly improved depressive symptoms but had only a small effect on how the brain responds to emotional stimuli. This contrasts with SSRIs, which often reduce emotional responsiveness alongside their antidepressant action. The findings suggest that psychedelic therapy may work through different neural mechanisms than conventional antidepressants.

Body mass index (BMI) does not predict responses to psilocybin

Journal of Psychopharmacology November 14, 2022 Meg J Spriggs, Bruna Giribaldi, Taylor Lyons et al. 15 citations

A fixed 25 mg dose of psilocybin produces similar acute psychedelic effects and improvements in well-being regardless of body mass index (BMI). Pooling data from three therapeutic studies, results support the null hypothesis that BMI does not predict overall intensity of the altered state, mystical experiences, perceptual changes, or emotional breakthroughs. There was weak evidence that lower BMI participants reported greater 'dread of ego dissolution,' but BMI did not meaningfully add to predictions beyond age, sex, and study. Mystical-type experiences and emotional breakthroughs strongly predicted well-being improvements, but BMI did not. These findings suggest body weight-adjusted dosing may be unnecessary, supporting fixed dosing to reduce practical and financial burdens on psychedelic therapy scalability.

Editorial: Psychedelic sociality: Pharmacological and extrapharmacological perspectives

Frontiers in Pharmacology July 22, 2022 Leor Roseman, Katrin H. Preller, Evgenia Fotiou et al. 15 citations

As psychedelic treatments become more mainstream and medicalized, there is a growing focus on their pharmacological and psychological effects on the individual, at the expense of their social and cultural dimensions. Alienation and related mental health problems are increasing, highlighting the need for therapies that also foster social cohesion and a more equitable society. Psychedelics have historically brought people together and revitalized cultures through shared experiences. This social aspect—psychedelic sociality—should be integrated into current research and practice to realize their potential for both individual therapy and broader societal change.

The flattening of spacetime hierarchy of the N,N-dimethyltryptamine brain state is characterized by harmonic decomposition of spacetime (HADES) framework.

National science review May 1, 2024 Jakub Vohryzek, Joana Cabral, Christopher Timmermann et al. 13 citations

The human brain's activity constantly reorganizes across space and time, and decomposing whole-brain recordings into harmonic modes reveals gradient-like patterns linked to different functions. Using the HADES framework, researchers analyzed brain activity in healthy participants after taking the serotonergic psychedelic DMT. They found significant decreases in contributions across most low-frequency harmonic modes during the DMT state. Specifically, the second functional harmonic, which represents the uni- to transmodal functional hierarchy, decreased, supporting the hypothesis that psychedelics alter this hierarchy. Dynamic measures of fractional occupancy, lifetime, and latent space precisely described the changes in the brain's spacetime hierarchical organization during the psychedelic state.

A reflection on paradigmatic tensions within the FDA advisory committee for MDMA-assisted therapy.

Journal of psychopharmacology (Oxford, England) April 1, 2025 Leor Roseman 12 citations

The FDA's rejection of MDMA-assisted therapy highlights a fundamental clash between two paradigms in psychopharmacology. The dominant paradigm treats drugs as having purely biological effects, with context treated as noise to be controlled. An emerging paradigm sees therapeutic effects as interactive with context. Psychedelics challenge the dominant model because researchers insist they are drugs combined with psychotherapy. The FDA's critique of the studies partly concerns experiential and psychotherapeutic elements, which the FDA claims not to regulate, creating paradoxes that suggest a need for regulatory and research shifts to integrate a new paradigm where drugs and psychotherapy interact.

On Revelations and Revolutions: Drinking Ayahuasca Among Palestinians Under Israeli Occupation

Frontiers in Psychology August 27, 2021 Leor Roseman, Nadeem Karkabi 11 citations

Ayahuasca rituals involving both Israelis and Palestinians can produce feelings of unity, but these feelings may mask a political status quo that marginalizes Palestinians. Interviews and observations of 31 participants revealed that the ritual structure avoided recognizing Palestinian national identity or acknowledging Israeli injustice. However, ayahuasca occasionally triggered revelatory events where individuals confronted the oppressive reality between the groups. These events evoked pain, anger, and guilt, leading to resistance against the hegemonic ritual structure and a desire to deliver an emancipatory message, often through song. This fidelity to the revealed truth sometimes expanded ayahuasca practices to other Palestinians and politicized the practice, illustrating the egalitarian revolutionary potential of psychedelics as analyzed through Badiou's theory.