Psilocybin Rewires How the Brain Processes Visual Context

Psychedelics are renowned for distorting reality, yet the precise neurological mechanics remain a subject of intense scrutiny. In a recent investigation, scientists utilised the visual system as a 'beachhead'—a strategic starting point—to decode these complex effects. The team employed a robust combination of psychophysics, computational modelling, and ultra-high field functional MRI to observe the brain under the influence of psilocybin.

The study focussed on the Ebbinghaus illusion, a famous visual test where the perceived size of a circle changes based on the context of the circles surrounding it. The researchers discovered that psilocybin significantly alters this contextual perception. Beyond mere observation, the fMRI data revealed distinct changes in 'contextual modulation' within the cortical responses to visual stimuli.

To make sense of these shifts, the team proposed a new computational model capable of linking the physical brain dynamics to the altered perceptual experience. The implications extend beyond simple geometry; the findings highlight that the alteration of contextual computations might be a general mechanism underlying how psychedelics influence the mind. By changing how the brain integrates background data, the drug fundamentally shifts how we construct our view of the world.