Cross-Species Evidence for Psilocin-Induced Visual Distortions: Apparent Motion Is Perceived by Both Humans and Rats
This cross-species experimental study (n=21 humans; n=10 rats) finds that psilocin (18.2mg/70kg for humans; 0.3mg/kg for rats) impairs the ability to distinguish between static and moving images in both humans and rats. In humans, the impairment aligns with psilocin plasma levels and self-reported hallucination intensity. In rats, the effect is specific to motion perception, providing the first evidence of psilocin-induced visual distortions across species.
Authors
- Tomáš Páleníček
- František Tylš
- Martin Brunovský
Published
Abstract
Background
Psychedelics, particularly psilocin, are increasingly being studied for their mind-altering effects and potential therapeutic applications in psychiatry. Visual hallucinations, especially the illusion of motion in static images, are a hallmark of their action. Despite growing interest, the underlying mechanisms remain poorly understood, as their systematic evaluation in both humans and animals is challenging.
Methods
To investigate psilocin-induced visual distortions, we designed a 2-choice visual discrimination task. Human participants and male rats indicated whether an image appeared static or moving while the image either actually moved or did not. In humans, performance was compared with self-reported hallucination intensity, Altered States of Consciousness scale scores, and psilocin plasma levels. Rats were tested in 2 distinct tasks, a luminance-based task and a motion-based task. Their performance was evaluated alongside decision time.
Results
Both species exhibited significant impairment in distinguishing static from dynamic visual stimuli while under psilocin’s influence. In humans, this impairment followed the time course of psilocin plasma levels and hallucination intensity. In rats, psilocin selectively impaired performance in the motion-based task, while performance in the luminance-based task remained intact, indicating a specific effect on visual perception. Decision time was linked to discrimination impairment.
Conclusions
Psilocin impaired static-dynamic discrimination in both species, providing the first evidence that rats experience visual distortions similar to those reported by humans. The correlations between discrimination impairment, psilocin levels, and hallucination intensity in humans reinforce psilocin’s effects on visual perception. This approach provides a valuable tool for investigating the neurobiology of altered visual perception in drug-induced states and psychiatric conditions.
Research Summary of 'Cross-Species Evidence for Psilocin-Induced Visual Distortions: Apparent Motion Is Perceived by Both Humans and Rats'
Introduction
Vejmola and colleagues situate their study within evidence that psychedelics, particularly psilocybin/psilocin, produce visual hallucinations and distortions such as apparent motion, contour undulation and geometric transformations. They note that 5-HT2A receptor agonism is central to these effects, that these receptors are abundant in visual pathways, and that altered 5-HT2A signalling has been implicated in visual hallucinations in clinical conditions such as Parkinson's disease and schizophrenia. Prior animal observations (disorganised behaviour, abnormal tracking or reaching at nonexistent objects across species) suggest cross-species effects, but until now no systematic, objective measurement of psychedelic-induced visual distortions in animals has been reported. To address this gap, the investigators developed a 2-choice visual discrimination paradigm applied in parallel to humans and rats. They hypothesised that psilocin would impair the capacity to distinguish static from dynamic images, yielding a tendency to misclassify static stimuli as moving. In humans, the design linked behavioural performance to self-reported hallucination intensity and plasma psilocin; in rats, decision time was used as an additional objective marker. The study aimed to provide the first objective, cross-species comparison of drug-induced apparent motion and to establish a preclinical model for studying the neurobiology of visual hallucinations.
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Study Details
- Study Typeindividual
- Journal
- Compounds
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- APA Citation
Vejmola, Č., Šíchová, K., Syrová, K., Janečková, L., Koudelka, V., Tesař, M., Nikolič, M., Viktorinová, M., Tylš, F., Korčák, J., Viktorin, V., Kelemen, E., Nekovářová, T., Brunovský, M., Horáček, J., Kuchař, M., & Páleníček, T. (2025). Cross-Species Evidence for Psilocin-Induced Visual Distortions: Apparent Motion Is Perceived by Both Humans and Rats. Biological Psychiatry Global Open Science, 5(5), 100524. https://doi.org/10.1016/j.bpsgos.2025.100524
References (10)
Papers cited by this study that are also in Blossom
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Vollenweider, F. X., Kometer, M. · Nature Reviews Neuroscience (2010)
Hanks, J. B., González-Maeso, J. · ACS Chemical Neuroscience (2012)
Tylš, F., Páleníček, T., Kadeřábek, L. et al. · Behavioural Pharmacology (2016)
Bravermanová, A., Viktorinová, M., Tylš, F. et al. · Psychopharmacology (2018)
Madsen, M. K., Fisher, P. M., Burmester, D. et al. · Neuropsychopharmacology (2019)
Cited By (1)
Papers in Blossom that reference this study
Scholle, P., Wenke, Š., Nekovářová, T. et al. · Journal of Psychopharmacology (2026)
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