A qualitative report on the subjective experience of intravenous psilocybin administered in an FMRI environment

Psilocybin is the active component of so‑called magic mushrooms and acts primarily at serotonin receptors (notably 5HT2A, 5HT2C and 5HT1A). Earlier clinical and anecdotal literature documented a wide range of subjective effects including visual distortions, changes in time perception, alterations of mood and cognition, mystical‑type experiences and occasional lasting personal meaning. Much of that historical research was curtailed by legal restrictions, and contemporary studies tend to quantify experience using psychometric instruments (for example the 5D‑ASC and Hallucinogen Rating Scale). The authors note that such scales may constrain reporting and miss uncommon effects or the influence of unusual settings. This report describes an exploratory phenomenological investigation of 15 volunteers with prior psychedelic experience who received intravenous psilocybin while undergoing functional MRI. Turton and colleagues set out to document, in participants' own words and through Interpretative Phenomenological Analysis (IPA), the subjective structure of the psilocybin experience when delivered intravenously in the scanner environment, and to compare these reports with those in the existing literature. The study aims to highlight reproducible experiential categories and to identify phenomena warranting further focused qualitative or neurobiological investigation.

Fifteen healthy volunteers (10 male, 5 female; mean age 34.1, SD 8.2) who reported prior psychedelic use were recruited and screened with medical, psychiatric and laboratory assessments. Standard exclusions applied, including age under 27, pregnancy, current or past diagnosed psychiatric disorder in the participant or a first‑degree relative, substance dependence, cardiovascular disease, claustrophobia or significant adverse responses to hallucinogens. Participants completed baseline anxiety and depression measures (STAI and BDI). Each participant underwent two consecutive 18‑minute fMRI functional scans separated by at least seven days. Cannulation was performed and infusions (placebo saline and psilocybin) were given manually over 60 seconds beginning six minutes into each scan. The reported psilocybin dose was 2 mg IV, described by the authors as producing subjective effects comparable to approximately 15 mg orally and therefore a moderate dose. Participants were told there would be one placebo and one psilocybin scan and were blinded to the order; the extracted text also elsewhere states that saline was given in the first scan and psilocybin in the second, an inconsistency in the source that is not resolvable from the provided text. During each scan participants completed a set of visual analogue scales (VAS) derived from the 5D‑ASC at four time points (start of scan, immediately before infusion, 5 minutes and 12 minutes post‑infusion) to rate intensity and other dimensions. After the second (psilocybin) scan all participants undertook a videotaped semi‑structured interview conducted by RCH, using the VAS items as prompts and asking further open questions (for example, first noticed effect and which scan contained psilocybin). Interviews were transcribed and analysed by a researcher not involved in data collection (ST) using Interpretative Phenomenological Analysis. The analyst engaged in reflexive practice, iterative transcription review, detailed annotation, generation of themes at the individual level and subsequent grouping into superordinate themes across participants.

Nine broad phenomenological categories emerged from the IPA: onset and intensity of effects; perceptual changes (visual, auditory, somatosensory, proprioceptive); cognitive changes; mood alterations; effects of memory; spiritual or mystical‑type experiences; aspects relating to the scanner and research environment; comparisons with other experiences; and participants' individual interpretations. Onset and intensity: All participants reported a rapid onset described as sudden and intense, with peak effects lasting around 10–15 minutes and fading thereafter; residual mild effects were still present during interviews. Participants described the experience occurring in waves. Two participants judged the overall intensity low, six described it as very intense and the remainder as intense or occasionally overwhelming. All participants correctly identified receiving psilocybin in the second scan (per the extracted text), and six reported mild perceptual changes during the placebo scan. Perceptual and sensory phenomena: Every participant reported visual effects, commonly fractal or geometric patterns, colour changes and static objects becoming dynamic. Twelve reported somatic sensations such as tingling, warmth or a sense of ‘melting’ into surroundings. Thirteen participants experienced time distortions (both acceleration and timelessness). Nine reported altered spatial perspective and seven noted distortions of the scanner sounds; five described instances of synaesthesia in which scanner noises influenced visual imagery. Cognition and sense of self: Thirteen participants reported altered cognition, typically muddled or fragmented thinking; eight described freer, less constrained thought processes. Seven described derealisation or a transported sense of place, and three reported periods of ‘thoughtlessness’. Ten participants reported changes in sense of self ranging from reduced attachment to the body to complete ego dissolution. Nine participants described a perceived loss of control and five reported some psychological resistance to the effects. Mood and memory: Positive mood effects predominated: seven reported joy, six laughter, and three euphoria; three reported no mood change. All participants experienced anticipatory anxiety before infusion, which generally resolved after onset; only two reported persistent anxiety afterward. Very few participants reported autobiographical memories intruding, though one reported re‑experiencing a distressing memory accompanied by intense emotion. Scanner and environment: Eleven participants judged the scanner environment negatively—terms included ‘strange’, ‘enclosed’, ‘clinical’ and ‘sensory deprivation’—and nine preferred more natural settings for psychedelic experiences. The centrally displayed fixation cross was a focal point for many (nine reported it as central to visual hallucinations). Despite discomfort or preference for a different setting, participants tolerated the environment and none attempted to leave. Spiritual/mystical aspects and interpretation: Reports of spiritual or mystical qualities were mixed. Some participants described awe, a sensed external presence or potentially meaningful experiences; others attributed interpretations to personal belief or cultural background. Eleven participants rated the overall experience as pleasant or positive, four as neutral but intense, and none expressed regret. Several compared the IV psilocybin experience to prior drug experiences or to deep meditation; two preferred intravenous administration for shorter duration and reduced nausea. Quantitative note: The extracted text states that all VAS items were rated significantly higher after psilocybin than placebo except for measures of fear and suspiciousness (t tests, P = 0.05), though full tabulated data are not reproduced in the provided extraction. Neuroimaging: the authors report reductions in cerebral blood flow in multiple cortical and subcortical regions, including the posterior cingulate cortex, a hub of the Default Mode Network, which they link to alterations in self‑related processing.

Turton and colleagues interpret their findings as broadly consistent with prior literature on psilocybin and altered states of consciousness: common themes such as vivid visual phenomena, time and self‑distortions, feelings of merging or ‘melting’, and occasional mystical‑type experiences were reproducible across participants. The investigators emphasise that several of the most unusual phenomena—timelessness, depersonalisation, ego dissolution and sensed external presences—tended to occur during particularly intense phases of the drug effect. The authors discuss limitations that could have shaped reports. They note potential priming from repeated completion of the VAS and from participants' awareness of taking part in psilocybin research (demand characteristics), the influence of cultural and subcultural language around psychedelics, and the conspicuous clinical and scanner setting which many participants felt was sub‑optimal for spiritual experiences. Conducting interviews immediately after the scan is presented as a double‑edged choice: it reduces memory decay and rationalisation but may limit participants' capacity to interpret and articulate the experience. Methodological reflections are offered on the use of Interpretative Phenomenological Analysis: the authors acknowledge that IPA accepts the impossibility of accessing a purely pre‑reflective experience and therefore frames findings as interpretations shaped by both participant and analyst. The sample size is described as relatively large for a phenomenological study; this breadth reduced the depth of individual accounts but allowed identification of reproducible phenomena across subjects. Finally, the paper links phenomenology to neuroimaging findings, suggesting that observed reductions in cerebral blood flow in areas such as the posterior cingulate cortex (part of the Default Mode Network) may relate to changes in self‑related processing and the unusual experiential states reported. The authors propose further work to correlate specific neural changes with the phenomenological themes identified and recommend further focused qualitative studies with smaller samples and more directed interviews to deepen interpretation and explore individual differences.