Cross-Species Evidence for Psilocin-Induced Visual Distortions: Apparent Motion Is Perceived by Both Humans and Rats.

Psilocin, the active compound in psychedelic mushrooms, impairs the ability to distinguish between static and moving images in both humans and rats. In a visual discrimination task, human participants and male rats were asked to judge whether an image was static or moving. Under psilocin, both species showed significant difficulty in this task. In humans, the impairment tracked psilocin plasma levels and self-reported hallucination intensity. In rats, psilocin selectively disrupted performance in a motion-based task but not a luminance-based task, suggesting a specific effect on motion perception. Decision time was also linked to discrimination impairment. This is the first evidence that rats experience visual distortions similar to those reported by humans, offering a model for studying altered visual perception in drug-induced and psychiatric conditions.

Study at a glance

Abstract

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. 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. 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. 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.