A lasting impact of serotonergic psychedelics on visual processing and behavior
bioRxiv – July 03, 2024
Source: medRxiv/bioRxiv/arXiv
Summary
Recent findings reveal that serotonergic psychedelics, like psilocybin and LSD, can enhance visual processing even weeks after use. Participants showed slower responses and greater brain involvement in visual tasks, indicating a shift from top-down to bottom-up processing. This lasting effect suggests potential benefits for cognitive and perceptual therapies.
Abstract
Serotonergic psychedelics (e.g., psilocybin) have shown potential for treating psychiatric disorders, with therapeutic effects lasting weeks after a single dose. Predictive processing theories posit that psychedelics work by loosening priors or high-level beliefs, including ingrained biases that have become pathological, leading to shifts in bottom-up vs top-down information processing that reconfigure perception, cognition, and mood. Because 5-HT2A receptors, the primary target of psychedelics, are enriched in visual cortices, we investigated whether psychedelics alter visual processing in a manner consistent with predictive processing theories. People who recently (<3 weeks) used 5-HT2A-agonist psychedelics (psilocybin, LSD) exhibited slowed response latencies and increased cortical involvement in generating saccades to targets in predictable locations, along with a generalization of sensory prediction errors (i.e., deviance detection) during passive visual processing. Individuals who recently used a 5-HT1A- selective psychedelic (5-MeO-DMT) displayed similar changes in saccade production, but unaltered deviance detection, suggesting circuit-specific effects. Mice administered DOI (5- HT2A-agonist) exhibited altered deviance detection within primary visual cortex (V1), along with weakened top-down feedback to V1 from higher cortical area ACa. These results concord with the hypothesis that psychedelics shift the balance from top-down to bottom-up in sensory cortical circuits – an effect that persists beyond the acute exposure period.