Scientific Reports
January 29, 2024
Oris Shenyan, Matteo Lisi, John A. Greenwood et al.
13 citations
Visual hallucinations can be simple (flashes, patterns) or complex (objects, scenes). Two experimental methods—Ganzflicker (high-frequency flickering light) and Ganzfeld (uniform visual field deprivation)—induced hallucinations in healthy participants. Simple hallucinations were more common than complex ones under both conditions. Ganzflicker produced more simple hallucinations than Ganzfeld, while complex hallucinations occurred at similar rates. Consequently, the proportion of complex hallucinations was higher during Ganzfeld. Correlations in hallucination frequency and duration across conditions suggest shared mechanisms, likely involving visual cortex excitability. Simple hallucinations may stem from heightened bottom-up input, especially in Ganzflicker, while complex hallucinations may rely on top-down processes less influenced by visual stimulation.
Cell Reports
July 22, 2025
George Blackburne, Rosalind McAlpine, Marco S. Fabus et al.
10 citations
Inhaling a high dose of vaporized synthetic 5-MeO-DMT radically reorganizes low-frequency brain oscillations, making them heterogeneous, viscous, and nonrecurring, and halting their typical forward and backward travel across the cortex. This reorganization also causes broadband neural activity to become more stable and low-dimensional, with increased energy barriers for rapid global shifts. These findings, based on EEG data from 29 healthy individuals, provide a detailed account of how the drug sculpts human brain dynamics and reveal atypical cortical slow-wave behaviors relevant to neuroscientific models of serotonergic psychedelics.
bioRxiv (Cold Spring Harbor Laboratory)
October 7, 2024
George Blackburne, Rosalind McAlpine, Marco S. Fabus et al.
8 citations
preprint
A high dose of the psychedelic drug 5-MeO-DMT radically reorganizes low-frequency brain activity in 29 healthy individuals. Inhaling 12 mg of vaporized synthetic 5-MeO-DMT caused neural activity flows to become incoherent, heterogeneous, viscous, fleeting, and nonrecurring, ceasing typical traveling waves across the cortex. This reorganization led to slower, more stable, low-dimensional broadband activity with increased energy barriers to rapid global shifts. The findings provide the first detailed empirical account of how 5-MeO-DMT alters human brain dynamics, revealing novel cortical slow wave behaviors.
Neuroscience and Biobehavioral Reviews
July 1, 2026
Marcus J. Glennon, Catherine Bird, Prateek Yadav et al.
2 citations
Setting up a psychedelic research study involves a long, arduous, and Kafkaesque process with many unstandardised challenges. These complexities challenge existing assumptions about psychiatric prescribing, the placebo effect, and definitions of selfhood. This review brings together major UK psychedelic research teams to formalise these unique considerations, addressing sociocultural, political, legal, pharmacological, safety, study design, and experiential facets. It identifies continuing areas of debate and provides a practical, experience-based guide with recommendations for policymakers and future researchers intending to set up a psychedelic study or clinical trial.
Journal of psychopharmacology (Oxford, England)
May 23, 2026
Joanna Kuć, Rosalind McAlpine, Amelia Sellers et al.
A short-acting psychedelic, 5-MeO-DMT, shifts speech from external focus to introspection. In 29 participants who kept daily voice journals two weeks before and after a single 12 mg dose, language analysis showed increased cognitive words and fewer social words, while vocal quality changed with more jitter and shimmer. Baseline speech patterns predicted how prepared people felt, the intensity of emotional breakthrough, and later well-being. This is the first longitudinal study showing that vocal journaling can track and predict psychological transformation around a psychedelic retreat, offering a framework for monitoring preparation and integration periods.
BMJ Open
March 12, 2026
Rosalind McAlpine, Magdalena Jaglinska, Krisztina Jedlovszky et al.
A 21-day mobile-accessible programme called the Digital Intervention for Psychedelic Preparation (DIPP) is being tested for feasibility and preliminary efficacy in a randomised controlled trial. The study will recruit 40 non-treatment-seeking adults without a clinical diagnosis, randomly assigning them to either a guided meditation with music condition or a music-only condition. After the digital intervention, all participants will attend an in-person supervised psilocybin session with a standardised 25 mg dose. Primary outcomes include recruitment efficiency, retention, and adherence; secondary outcomes assess preparedness, quality of the psychedelic experience, and wellbeing, with follow-ups up to 9 months. The trial is registered as NCT06815653.
Open Science Framework
October 20, 2025
Natalia Fernandez‐Vinson, Roger Atkins, Marcus J. Glennon et al.
This registered clinical study investigates whether N,N-dimethyltryptamine (DMT), alone or combined with reactivating alcohol-related memories, can produce lasting changes in the brain, cognition, and drinking behavior in people with mild alcohol use disorder who are hazardous drinkers but not seeking treatment. Up to 120 participants will be assigned to one of four groups: alcohol memory retrieval plus DMT, alcohol memory retrieval plus placebo, control memory retrieval plus DMT, or control memory retrieval plus placebo. Drinking levels will be measured over three lab sessions and a nine-month follow-up using timeline follow-back and blood tests.
bioRxiv Preprint Server
August 22, 2025
Jeremy I Skipper, Daniel R Lametti, David W Green
preprint
Psychotic symptoms such as hearing voices or feeling that thoughts are inserted may arise from failures in the brain's prediction and self-monitoring systems. Normally, when people talk internally, the brain sends copies of motor commands to auditory regions and suppresses them, helping distinguish self-generated from external input. When this suppression malfunctions, predicted inner speech can become perceptually salient and misattributed as external. Neuroimaging meta-analyses showed that psychosis-spectrum participants had increased activity in motor-related regions for inner speech and decreased grey matter in auditory cortices and anterior cingulate cortex. These regions form inversely coupled networks, supporting a hierarchical predictive-processing account where disruption distorts self-awareness.
bioRxiv
April 21, 2025
Joanna Kuć, Rosalind McAlpine, Amelia Sellers et al.
preprint
After a single 12 mg dose of the psychedelic 5-MeO-DMT, people's speech patterns shifted toward more cognitive language and fewer social words, and their voices showed increased jitter and shimmer, indicating altered vocal quality. Baseline speech features predicted how psychologically prepared participants were, their anxiety about ego dissolution, emotional breakthrough, and later well-being. The findings suggest that analyzing voice journals can track a shift from external focus to introspection and serve as a tool for monitoring psychological transformation after psychedelic use.
arXiv (Cornell University)
September 30, 2024
Jeremy I Skipper, Joanna Kuć, Gregory M. Cooper et al.
Reducing attention to language in multimodal AI models makes their semantic spaces more similar to the phenomenology of altered states such as ego dissolution and unity reported in psychedelic and meditation experiences. When attentional weights were shifted away from language and vision in CLIP and FLAVA models, their embedding spaces aligned more closely with disembodied, unitive, and minimal phenomenal states than with anxiety or random text. This alignment was accompanied by blurred distinctions within and across semantic categories, such as 'giraffes' becoming more like 'bananas'. The findings suggest that language categorization contributes to the structure of ordinary consciousness, and its breakdown may underlie the phenomenology of altered states linked to improved mental health.
May 2, 2024
Jeremy I Skipper, George Fejer, Matthieu Koroma et al.
preprint
Language plays a generative role in shaping and sustaining consciousness, not merely reporting it. Cognitive neuroscientist Jeremy I. Skipper argues against localizationist models of language processing, emphasizing context-dependent and dynamic brain recruitment. Aphasic patients report loss of self-narrative and increased connectedness, paralleling psychedelic states where linguistic categories dissolve and ineffability arises. Potential neural mechanisms linking language disruption to psychedelic experiences are outlined. The UNITy Project aims to study post-acute meaning-making processes and predict changes in language and well-being after psychedelic sessions.
bioRxiv (Cold Spring Harbor Laboratory)
August 13, 2023
Oris Shenyan, Matteo Lisi, John A. Greenwood et al.
preprint
Hallucinatory experiences, defined as perception without external stimuli, occur in both pathological and non-pathological states and are divided into simple and complex types. Non-pathological visual hallucinations can be induced experimentally using different methods. This study compared two techniques: flicker and perceptual deprivation (Ganzfeld) in 20 participants, measuring hallucination frequency and complexity through button press, retrospective drawing, interviews, and questionnaires. Simple hallucinations were more common than complex hallucinations with both techniques. Flicker elicited more hallucinations on average, but Ganzfeld hallucinations lasted longer.
Neuroscience and Biobehavioral Reviews
September 1, 2026
Jeremy I Skipper, Daniel R Lametti, David W Green
Aberrations in inner speech are linked to psychotic symptoms such as thought insertion and auditory verbal hallucinations, which may arise from failures in prediction and source monitoring. Normally, efference copies of speech motor commands suppress auditory responses to self-generated input; if suppression malfunctions, predicted auditory input becomes perceptually salient. Impaired self-monitoring regions (e.g., anterior cingulate cortex) may cause inner speech to be misattributed as external. Neuroimaging meta-analyses of neurotypical participants and psychosis spectrum participants showed increased activity in motor-related regions (e.g., ventral premotor cortices) and decreased grey matter in auditory cortices and ACC. These regions form distinct, inversely coupled audiomotor networks, supporting the proposal that psychotic symptoms derive from hyperactivation in inner speech regions producing insufficiently suppressed efference copy signals.
arXiv Preprint Archive
March 28, 2025
Marcus J. Glennon, Catherine Bird, Prateek Yadav et al.
Setting up a psychedelic study is a long and complex process that presents unique challenges not yet standardized. This review brings together major UK research teams to formalize these considerations, identify ongoing debates, and provide a practical guide for researchers and policymakers. It addresses challenges to existing assumptions about psychiatric prescribing, the placebo effect, and definitions of selfhood. The paper can be read end-to-end or used as a manual with sections for specific needs.
Neuroscience and Biobehavioral Reviews
September 1, 2022
Jeremy I Skipper
Language, especially inner speech, is hypothesized to generate and sustain higher-order self-awareness. A 'HOLISTIC' model proposes a core set of inner speech production regions that initiate the experience of feeling and hearing words, which acquire affective qualities through activation of associated sensory, motor, and emotional representations in a largely unconscious dynamic periphery distributed throughout the brain. Responding to these words sustains network activity involving default mode activation and prefrontal and thalamic/brainstem selection of contextually relevant responses. The model offers a more parsimonious account of the neural correlates of consciousness and has implications for mental health and wellbeing.
George Blackburne, Alberto Liardi, Jeremy I Skipper et al.
preprint
The relationship between subjectivity and its physical substrate can be understood through compatibilist emergence, which accounts for how nature can host new dynamical laws at higher scales. The autopoietic character of life may require and promote the kind of emergence necessary, though not sufficient, for consciousness.