The mixed serotonin receptor agonist psilocybin reduces threat-induced modulation of amygdala connectivity
NeuroImage Clinical – August 22, 2015
Source: OpenAlex
Summary
Psilocybin significantly alters emotional processing by shifting biases from negative to positive stimuli. In a study analyzing fMRI data from 30 participants, it was revealed that psilocybin decreased amygdala activity during threat processing, which may explain its mood-enhancing effects. Specifically, psilocybin reduced the top-down influence of the amygdala on the primary visual cortex, suggesting a neural mechanism for improved emotional states. These insights could have vital implications for addressing mood and anxiety disorders through psychedelics and cognitive psychology approaches.
Abstract
Stimulation of serotonergic neurotransmission by psilocybin has been shown to shift emotional biases away from negative towards positive stimuli. We have recently shown that reduced amygdala activity during threat processing might underlie psilocybin's effect on emotional processing. However, it is still not known whether psilocybin modulates bottom-up or top-down connectivity within the visual-limbic-prefrontal network underlying threat processing. We therefore analyzed our previous fMRI data using dynamic causal modeling and used Bayesian model selection to infer how psilocybin modulated effective connectivity within the visual-limbic-prefrontal network during threat processing. First, both placebo and psilocybin data were best explained by a model in which threat affect modulated bidirectional connections between the primary visual cortex, amygdala, and lateral prefrontal cortex. Second, psilocybin decreased the threat-induced modulation of top-down connectivity from the amygdala to primary visual cortex, speaking to a neural mechanism that might underlie putative shifts towards positive affect states after psilocybin administration. These findings may have important implications for the treatment of mood and anxiety disorders.