Schedule of Events | Symposia

Effects of Psilocybin on Brain Representations of Movies

Poster Session C - Sunday, March 30, 2025, 5:00 – 7:00 pm EDT, Back Bay Ballroom/Republic Ballroom

Brian Winston¹ (bwinsto2@jh.edu), Gabi Lofland², Janice Chen¹, Frederick Barrett²; ¹Johns Hopkins University, ²Johns Hopkins School of Medicine

The classic psychedelic drug psilocybin is known to perturb the functional landscape of the human brain during unconstrained perception and cognition. However, the degree to which psilocybin alters processing of naturalistic, multi-modal stimuli is not well characterized. We sought to investigate whether psychedelics alter brain representations of real-world content in sensory, associative, and/or high-level brain regions. 12 participants (of a planned 30) watched nine short audiovisual movies totaling one hour while undergoing functional MRI during the acute effects of 10mg psilocybin and placebo administered at separate visits. Movies were segmented into events by human raters. To examine how psilocybin influences brain representations of movie content across the cortical processing hierarchy, intersubject pattern correlation (pISC) of event-wise multivoxel patterns (MVPs) were calculated and averaged across events separately for the placebo and psilocybin scans. The correlation between each subject’s MVP and the remaining group’s average MVP in primary auditory and visual cortices (A1, V1), posterior-medial cortex (PMC), medial prefrontal cortex (mPFC) and angular gyrus (AG) were averaged across events and movies and compared between drug conditions using two-tailed t-tests. pISC was reduced in all ROIs in the psilocybin condition after Bonferroni correction (p < 0.01). This suggests that altered stimulus processing as early as primary sensory cortex could contribute to psilocybin-induced perceptual changes. Follow-up analyses will incorporate eye-tracking and verbal recall of movies to investigate whether changes in pISC reflect altered neural processing or simply differences in attention to the stimulus.

Topic Area: LONG-TERM MEMORY: Episodic