The psychedelic psilocybin and light exposure have similar and synergistic effects on gene expression patterns in the visual cortex

Psilocybin, a psychedelic compound found in specific hallucinogenic mushrooms, is known to induce changes in visual perception and experience in humans. However, there is little knowledge of the molecular mechanisms through which psilocybin affects vision-associated regions in the brain, such as the visual cortex. The current study determined both psilocybin-induced and experience-dependent changes (exposure to light) in visual cortex gene expression in mice. Of great interest, psilocybin induced robust gene expression changes in the visual cortex that closely mirror light-induced gene expression changes, even when the mice are kept in the dark. These gene expression changes correspond to specific molecular pathways, including synaptic functioning, and represent genes expressed in specific subtypes of neurons. In addition, exposure to both psilocybin and light induced synergetic changes in genes involved in epigenetic programming. Overall, the study determined that psilocybin induces robust changes in gene expression in the visual cortex that may have functional consequences in visual perception both in the absence and in synergy with visual experience.