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Robin Carhart-Harris

Imperial College London, Multidisciplinary Association for Psychedelic Studies

351 papers in the library · 30,431 citations · publishing 2007-2026

Papers

Psychedelics in developmental stuttering to modulate brain functioning: a new therapeutic perspective?

Front Hum Neurosci June 19, 2024 Giuseppe Pasculli, Pierpaolo Busan, Eric S. Jackson et al. 5 citations

Developmental stuttering involves speech-motor disruptions linked to metabolic and network anomalies in the brain, particularly in the default mode and social-cognitive networks. These networks also influence social anxiety and avoidance, which often accompany persistent stuttering. Psychedelic compounds can modify brain metabolism and connectivity in these networks and have shown clinical benefits for conditions like depression and PTSD that share features such as rumination and social anxiety. Although no controlled trials have been conducted, anecdotal reports suggest psychedelics might alleviate stuttering and its associated symptoms. The authors argue that psychedelics warrant investigation in randomized clinical trials for developmental stuttering.

LSD flattens the hierarchy of directed information flow in fast whole-brain dynamics

bioRxiv (Cold Spring Harbor Laboratory) April 28, 2024 Kenneth Shinozuka, Prejaas K.b. Tewarie, Andrea I. Luppi et al. 5 citations preprint

LSD weakens the brain's directed connectivity hierarchy by increasing the balance between senders and receivers of neural signals. This finding supports the REBUS theory, which proposes that psychedelics flatten the hierarchy of information flow in the brain. Analyzing magnetoencephalography data from 16 healthy participants given 75 micrograms of intravenous LSD, the study found that LSD diminishes the asymmetry of directed connectivity averaged over time. Machine learning classifiers distinguished LSD from placebo more accurately when trained on hierarchy metrics than on traditional functional connectivity measures.

Autonomic Nervous System activity correlates with peak experiences induced by DMT and predicts increases in wellbeing

bioRxiv March 20, 2024 Valerie Bonnelle, Amanda Feilding, Fernando E. Rosas et al. 5 citations preprint

Intense positive emotional experiences induced by psychedelics, known as 'peak experiences', are strong predictors of positive outcomes in psychedelic-assisted therapy. This study investigated how the autonomic nervous system (ANS) relates to such experiences. Analyzing electrocardiogram data from 17 participants who received DMT or placebo, researchers found that coactivation of the sympathetic and parasympathetic branches of the ANS during the DMT experience was strongly correlated with ratings of 'Spiritual Experience' and 'Insightfulness', and also linked to improved wellbeing two weeks later. Additionally, the balance between these branches before DMT injection predicted 'Insightfulness' scores. These findings demonstrate the ANS's involvement in psychedelic-induced peak experiences and suggest potential for biofeedback tools to enhance therapy.

Improvements in well-being following naturalistic psychedelic use and underlying mechanisms of change in older adults: A prospective cohort study.

Research Square March 8, 2024 Hannes Kettner, Leor Roseman, Adam Gazzaley et al. 5 citations

Older adults (age 60+) who participated in a guided psychedelic group retreat showed significant improvements in well-being, with larger gains among those with a prior psychiatric diagnosis. Compared to younger adults, older adults experienced weaker acute psychedelic effects, and these effects did not predict well-being changes. Instead, a sense of communitas—the relational or social connection during the group session—predicted well-being improvements in older adults, suggesting that the social context of psychedelic therapy may be especially important for this age group.

The Temporal Trajectory of the Psychedelic Mushroom Experience Mimics the Narrative Arc of the Hero’s Journey

Research Square (Research Square) February 23, 2024 Ari Brouwer, Joshua K. Brown, Earth Erowid et al. 5 citations

Psychedelic therapy may work partly because its temporal structure mirrors the narrative arc of the Hero's Journey. A qualitative analysis of self-reported onset (comeup) and offset (comedown) phases of psilocybin experiences found that the comeup is more often characterized by negatively valenced feeling states, while the comedown is more often characterized by positively valenced feeling states resembling recovery from illness or adversity. This trajectory suggests that initially distressing altered states can ultimately resolve distress, offering a framework for understanding the therapeutic benefits of psychedelics.

LSD-induced increase of Ising temperature and algorithmic complexity of brain dynamics

bioRxiv August 29, 2022 Giulio Ruffini, Giada Damiani, Diego Lozano-Soldevilla et al. 5 citations preprint

Using fMRI data from fifteen people who took LSD or a placebo, researchers modeled brain dynamics with an Ising spin model to test whether psychedelics push the brain into a more disordered state. LSD increased the Ising temperature of brain activity, moving it further away from a critical point (the edge between order and disorder) into a more disordered, paramagnetic phase. This shift was accompanied by a decrease in interhemispheric connectivity, especially between corresponding regions in the two hemispheres. Algorithmic complexity of brain signals also increased with LSD. The findings suggest LSD loosens homotopic connections, driving the brain into a more flexible, complex state, consistent with theories that psychedelics increase neural entropy.

Mapping Pharmacologically-induced Functional Reorganisation onto the Brain’s Neurotransmitter Landscape

bioRxiv (Cold Spring Harbor Laboratory) July 13, 2022 Andrea I. Luppi, Justine Y. Hansen, R. Adapa et al. 5 citations preprint

Psychoactive drugs reshape brain function by engaging multiple neurotransmitter systems simultaneously. By mapping the distribution of 19 neurotransmitter receptors and transporters (via PET) and the connectivity changes caused by 10 drugs (anesthetics, psychedelics, and stimulants), the study shows that drug effects are organized along hierarchical gradients of brain structure and function. Additionally, brain regions susceptible to drug-induced changes are also vulnerable to structural alterations from brain disorders. These findings reveal systematic links between molecular neurochemistry and large-scale functional reorganization.

Psychedelics and schizophrenia: Distinct alterations to Bayesian inference

bioRxiv February 1, 2022 Hardik Rajpal, Pedro A. M. Mediano, Fernando E. Rosas et al. 5 citations preprint

Schizophrenia and drug-induced states from LSD and ketamine both increase neural signal diversity, but they differ in how information flows in the brain. In schizophrenia, transfer entropy from the front to the back of the brain is increased, whereas under both drugs it is reduced overall. These differences can be modeled by altering Bayesian inference within a predictive processing framework: drug effects correspond to reduced precision of prior beliefs, while schizophrenia corresponds to increased precision of sensory information. The findings clarify similarities and differences between these altered states, with potential implications for understanding consciousness and developing mental health treatments.

What it is like to be a bit: An Integrated Information Decomposition account of emergent mental phenomena

Andrea I. Luppi, Pedro A. M. Mediano, Fernando E. Rosas et al. 5 citations preprint

Consciousness can be understood not as a single unified thing but as composed of distinct information-theoretic elements. A new approach called Integrated Information Decomposition (ΦID) shifts from measuring how much integrated information a system has to analyzing its composition. This provides a formal way to determine whether consciousness is an emergent phenomenon based on that composition. Two organisms can have the same amount of integrated information yet differ in its composition. A new measure, ΦR, and the ΦR-ing rate quantify how efficiently an entity uses information for conscious processing. This decomposition identifies qualitatively different 'modes of consciousness,' enabling mapping between phenomenology and information-theoretic structure, starting with selfhood.

A short-acting psychedelic intervention for major depressive disorder: a phase IIa randomized placebo-controlled trial.

Nat Med February 16, 2026 David Erritzøe, Tommaso Barba, Tiffanie Benway et al. 4 citations

A single 21.5-mg intravenous dose of the psychedelic DMT, given with psychotherapeutic support, produced a rapid and significant reduction in depressive symptoms in adults with moderate-to-severe major depressive disorder. In a double-blind, placebo-controlled trial with 34 participants, those receiving DMT showed a greater decrease in depression scores at two weeks compared to placebo. Antidepressant effects persisted up to three months in an open-label phase. Adverse events were mostly mild to moderate, and no serious adverse events occurred.

Exploring the Therapeutic Effects of Psychedelics Administered to Military Veterans in Naturalistic Retreat Settings

Brain and Behavior July 1, 2025 Megan Calnan, Grace Blest‐hopley, Chris Busch et al. 4 citations

Military veterans who attended psilocybin or ayahuasca retreats showed significant improvements in eight measures of mental health and community reintegration, with the largest gains in depression (29.1% reduction on the PHQ-9) and PTSD (26.1% reduction on the PCL-5). Psilocybin retreats produced greater improvements on seven of eight outcomes, while ayahuasca retreats yielded slightly larger PTSD reductions (26.4% vs. 24.8%). Male participants improved more on all outcomes except PTSD, where females showed a larger reduction (32.1% vs. 24.1%). Veterans with worse initial symptoms benefited most. The findings suggest psychedelic retreats could offer a holistic treatment framework addressing psychological well-being, community factors, and civilian reintegration.

Exploring serotonergic psychedelics as a treatment for personality disorders.

Neuropharmacology July 1, 2025 Brennan M. Carrithers, Daniel E. Roberts, Brandon M Weiss et al. 4 citations

Psychedelic therapy may hold potential for treating personality disorders by promoting adaptive changes in personality, though rigorous research is lacking. This review first examines research on psychedelics in individuals with personality disorders using the DSM-5-TR categorical model, then applies the dimensional DSM-AMPD framework to explore how psychedelics might affect self-functioning, interpersonal functioning, and pathological personality traits. The authors discuss clinical relevance, safety considerations, gaps, and recommendations for treating these complex populations.

Micro-phenomenology of immersion and perceived presences under DMT

PsyArXiv May 14, 2025 James W. Sanders, Raphaël Millière, Ema Demšar et al. 4 citations preprint

Under DMT, immersive experiences and perceived presences follow a consistent structural pattern: bodily sensations arise first, then visual and auditory elements, and only after multisensory integration and 3D spatial characteristics develop do perceived sentient presences emerge. Micro-phenomenological interviews with 23 participants who received intravenous DMT (20mg) during fMRI-EEG recordings identified 125 phenomenological categories structuring immersion, including modal sensory dimensions, amodal feelings, self/world configurations, and social engagement modes. Perceived presences varied in sensory manifestation, semantic complexity, and social interaction modes. The findings advance understanding of non-ordinary states of consciousness and support future neurophenomenological research.

Dissociable effects of psilocybin and escitalopram for depression on processing of musical surprises

Molecular Psychiatry April 26, 2025 Rebecca Harding, Neomi Singer, Talma Hendler et al. 4 citations

Psilocybin therapy reduces anhedonia more than the SSRI escitalopram in major depressive disorder, yet escitalopram dampens emotional responses to musical surprises while psilocybin therapy preserves them. Escitalopram increases brain activity in memory and emotion regions during musical surprises, whereas psilocybin therapy decreases activity in the ventromedial prefrontal cortex and angular gyrus and increases sensory region activation. These contrasting neural and behavioral effects suggest fundamentally different treatment mechanisms: psilocybin may maintain subjective responses by reducing the salience of prediction errors or strengthening hedonic expectations, while escitalopram may weaken hedonic priors.

The Role of the Dorsolateral Prefrontal Cortex in Ego Dissolution and Emotional Arousal During the Psychedelic State.

Human Brain Mapping April 1, 2025 Clayton R. Coleman, Kenneth Shinozuka, Robert Tromm et al. 4 citations

LSD alters consciousness by changing connectivity between the dorsolateral prefrontal cortex (DLPFC), thalamus, and visual areas. In healthy participants, stronger functional connectivity between the left and right DLPFC, thalamus, and fusiform face area correlated with greater ego dissolution. Emotional arousal was linked to increased connectivity between the right DLPFC, intraparietal sulcus, and salience network. A confirmatory reverse analysis supported these findings. Magnetoencephalography data showed that LSD increased theta-band information flow from the thalamus to the DLPFC, supporting the idea that disrupted thalamic gating underlies ego dissolution. The results clarify the DLPFC's role in LSD-induced altered states.

DMT-induced shifts in criticality correlate with ego-dissolution

bioRxiv February 8, 2025 Mona Irrmischer, Marco Aqil, Lisa Luan et al. 4 citations preprint

The psychedelic DMT shifts brain oscillations away from criticality—a state thought to support healthy brain function—in alpha and adjacent frequency bands, moving toward subcritical regimes. Entropy increases while complexity decreases during this shift. The magnitude of the criticality shift in alpha and theta bands correlates with the intensity of ego-dissolution, a core feature of the psychedelic experience. These results suggest that altered proximity to critical brain dynamics may underlie the neurological and subjective effects of psychedelics, with implications for understanding altered states of consciousness.

Long-term effects of psilocybin on dynamic and effectivity connectivity of fronto-striatal-thalamic circuits

bioRxiv (Cold Spring Harbor Laboratory) November 7, 2024 Lorenzo Pasquini, Jakub Vohryzek, Anira Escrichs et al. 4 citations preprint

Psilocybin induces fast and sustained improvements in mental well-being, yet its long-term mechanisms are not fully understood. Four weeks after a full dose, fronto-striatal-thalamic (FST) circuitry—involved in goal-directed behavior and motivation—shows increased dynamic activity and flexibility in healthy volunteers. Computational modeling indicates that reduced structural constraints on functional dynamics cause this increased flexibility. Long-term changes include increased bottom-up and reduced top-down information flow, mediated by serotonergic (5-HT2A) and dopaminergic (D2) receptor systems. This functional re-organization of FST circuits may represent a common mechanism underlying clinical improvements across neuropsychiatric disorders such as substance abuse, major depression, and anorexia.

Eigenmodes of the deep unconscious: The neuropsychology of Jungian archetypes and psychedelic experience.

PsyArXiv October 20, 2024 Hugh McGovern, Marco Aqil, Selen Atasoy et al. 4 citations preprint

Archetypes, as described by Carl Jung, can be understood through modern neuroscience. The article proposes that archetypes arise from a three-part interaction: subcortical systems provide an affective core, altered states like those induced by psychedelics generate archetypal imagery, and higher cortical areas encode archetypal stories. The Free Energy Principle and Predictive Processing are used as foundational frameworks. Archetypes may be transmitted socially, forming a collective unconscious through learning and attunement. The work offers testable hypotheses about the neurological bases of archetypes, aiming to bridge Jungian psychology with neuroscience and encourage empirical investigation.

Dynamic medial parietal and hippocampal deactivations under DMT relate to sympathetic output and altered sense of time, space, and the self.

bioRxiv : the preprint server for biology August 12, 2024 Lorenzo Pasquini, Alexander J. Simon, Courtney L. Gallen et al. 4 citations preprint

The psychedelic DMT rapidly alters consciousness, producing physical transcendence, vivid auditory distortions, and visual imagery. Using simultaneous fMRI and EKG data from 14 healthy volunteers before, during, and after intravenous DMT (versus placebo), a brain substate emerged immediately after injection characterized by deactivations in the hippocampus and medial parietal cortex alongside increased superior temporal lobe activity. Hippocampal and medial parietal deactivations correlated with disruptions in the sense of time, space, and self-referential processes, reflecting a deconstruction of ordinary consciousness. Superior temporal lobe activations correlated with audio/visual hallucinations and the experience of "entities.

Psychedelic Science of Spirituality and Religion: An Attachment-Informed Agenda Proposal

December 25, 2021 Aaron D. Cherniak, Joel Gruneau Brulin, Mario Mikulincer et al. 4 citations preprint

Combining attachment theory with the REBUS model offers a framework for understanding how psychedelic experiences can reshape spiritual and religious beliefs. Attachment theory holds that early caregiving relationships create internal working models that act as mental templates for later interpersonal and divine relationships. Psychedelic therapy may work by loosening rigid, defensive mental patterns—such as insecure attachment to others or God—while corrective relational experiences with a therapist or others amplify this effect. Three research proposals are outlined: individual attachment security predicts how people experience and integrate psychedelic sessions; effective psychedelic therapy should increase attachment security as a measurable outcome; and attachment-related processes—like feeling connected to others or God and reducing attachment-related anxieties—are key mechanisms in psychedelic treatment's clinical benefits.

Neural correlates of the DMT experience as assessed via multivariate EEG

bioRxiv July 18, 2019 Christopher Timmermann, Leor Roseman, Michael Schartner et al. 4 citations preprint

Intravenous DMT, a fast-acting psychedelic, markedly alters human brain activity. Compared with a placebo, DMT reduced oscillatory power in alpha and beta brainwaves and increased spontaneous signal diversity. Time-referenced analyses linked changes in subjective experience to changes in brain activity. Emergence of delta and theta frequency oscillations correlated with the peak of the experience, particularly its eyes-closed visual component. These findings advance understanding of the neurobiological underpinnings of immersive states of consciousness.

LSD alters eyes-closed functional connectivity within the early visual cortex in a retinotopic fashion

Journal of Vision September 1, 2016 Leor Roseman, Martin I. Sereno, Robert Leech et al. 4 citations

Under LSD, the visual cortex's resting-state functional connectivity (RSFC) becomes more dependent on its intrinsic retinotopic organization, as if the brain were processing actual visual input despite closed eyes. In 10 healthy subjects, RSFC between non-adjacent patches of V1 and V3 that represent congruent parts of the visual field (both horizontal or both vertical meridians) was significantly stronger than connectivity between incongruent patches (horizontal-vertical), compared to placebo. The difference between congruent and incongruent connectivity was greater under LSD (Cohen's d=1.6), suggesting that psychedelic imagery involves transient local retinotopic activation similar to that from visual stimulation.

Improved mental health outcomes and normalised spontaneous EEG activity in veterans reporting a history of traumatic brain injuries following participation in a psilocybin retreat

Frontiers in Psychiatry August 6, 2025 Grace Blest‐hopley, Giuseppe Pasculli, Simon Ruffell et al. 3 citations

Veterans with traumatic brain injuries who participated in psilocybin retreats showed improvements in PTSD, depression, and anxiety symptoms four weeks afterward. PTSD scores decreased by 50%, depression scores by 65%, and anxiety scores by 28%. Electroencephalography measurements revealed decreased delta and theta brainwave power in frontal and temporal regions, along with enhanced coherence in alpha and beta bands, suggesting improved cognitive control, emotional processing, and neural communication. The preliminary findings provide a rationale for larger controlled studies.

Perturbing whole‐brain models of brain hierarchy: An application for depression following pharmacological treatment

Annals of the New York Academy of Sciences July 21, 2025 Marcel Socoró-garrigosa, Yonatan Sanz Perl, Morten L. Kringelbach et al. 3 citations

The scale at which the brain represents information remains a key question in neuroscience. Evidence shows that information is encoded not just in localized areas but across distributed, hierarchical networks. The hierarchy of causal influences shaping brain activity patterns is a signature of different brain states, relevant to neuropsychiatric disorders. Using whole-brain models guided by the thermodynamics of mind framework, researchers estimated brain hierarchy and studied in-silico transitions in static functional connectivity. Applying this to major depressive disorder, they built resting-state whole-brain models of depressed patients before and after treatment with psilocybin or escitalopram.

LSD reconfigures the frequency-specific network landscape of the human brain

bioRxiv March 24, 2025 Kenneth Shinozuka, Mattia Rosso, Clayton R. Coleman et al. 3 citations preprint

LSD profoundly alters consciousness by reorganizing brain networks in specific frequency bands. Analyzing MEG data from 14 healthy participants, the substance enhances high alpha (12.1, 13.3 Hz) activity across all conditions and high beta (25.3 Hz) in three conditions, while suppressing low beta (18.1, 19.3 Hz) and low alpha (8.5 Hz). LSD also shifts network spatial distributions: low alpha moves anteriorly toward the motor cortex, high alpha becomes more localized to the visual cortex, and low beta expands over temporal and occipital cortices. These frequency- and region-specific changes add nuance to theories of network disintegration under psychedelics.