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.

In this study, we explored how psilocin, a compound derived from psilocybin in magic mushrooms, alters visual perception in humans and rats. Using a visual discrimination task, both species were tested on their ability to distinguish static from dynamic images. Psilocin caused humans to misclassify static images as dynamic and induced similar visual distortions in rats. This is the first study to demonstrate that rats experience psilocin-induced visual distortions comparable to those reported by humans, thereby providing a valuable foundation for further research on visual alterations across species.

3rd Faculty of Medicine Charles University Prague Czechia

Center for Advanced Studies of Brain and Consciousness National Institute of Mental Health Klecany Czechia

Clinical Research Program National Institute of Mental Health Klecany Czechia

Faculty of Science Charles University Prague Czechia

Forensic Laboratory of Biologically Active Substances Department of Chemistry of Natural Compounds University of Chemistry and Technology Prague Czechia

Psychedelic Research Center National Institute of Mental Health Klecany Czechia

Sleep and Chronobiology Research Center National Institute of Mental Health Klecany Czechia

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