Biology subjects

D'Amelio, T.

Publications and source records attributed to D'Amelio, T..

3 recordsLinked to original sources

bioRxiv2025

Psilocybin-induced modulation of visual salience processing

Psychedelic compounds significantly reshape conscious perception, yet the implications of these alterations for complex visual-guided behaviors remain poorly understood. We investigated how psilocybin modulates visual salience processing during natural scene perception. Twenty-three participants completed eye-tracking tasks under self-blinded low and high doses of psilocybin, in a naturalistic design with experimental conditions unknown to participants and researchers. Subjects viewed natural scenes while their gaze patterns were recorded and analyzed in relation to normative computational saliency maps generated using a deep learning model of visual attention. Results revealed increased fixation on salient image regions and reduced inter-fixation distance under the high-dose condition, suggesting heightened sensitivity to visual salience and more localized gaze behavior. The Shannon entropy of fixations on high-saliency regions indicated a more exploratory and less predictable visual scanning of the images. Complementary EEG recordings showed broadband spectral power reductions and increased Lempel-Ziv complexity, with delta power negatively correlating with salience metrics. These findings suggest psilocybin enhances bottom-up attentional control while weakening top-down modulation, consistent with theoretical models positing facilitated bottom-up information flow under the acute effect of psychedelics.

neuroscience↗

bioRxiv2024

Time-resolved neural and experience dynamics of medium- and high-dose DMT

N,N-Dimethyltryptamine (DMT) is a fast-acting psychedelic drug that induces a radical reorganisation of conscious contents and brain dynamics. However, our understanding of how brain dynamics support psychedelic-induced conscious states remains unclear. We therefore present a repeated-measures dose-dependent study of the subjective and neural dynamics induced through DMT under naturalistic conditions. Nineteen participants received either a 20mg or 40mg dose of freebase DMT across two sessions in a blinded, counterbalanced order. Electroencephalography (EEG) data and time-resolved measures of subjective experience (Temporal Experience Tracing) were collected. Both doses of DMT induced rapid changes in experience dimensions, with the 40mg dose inducing more extreme visual hallucinations and emotionally intense experiences. Strikingly, lempel-ziv complexity, previously hailed as a robust phenomenological correlate within the psychedelic-state, was the least strongly associated neural marker. These findings suggest that the relationship between neural complexity and phenomenology in psychedelic states is less clear than originally hypothesised.

neuroscience↗

bioRxiv2023

Acute effects of psilocybin on the dynamics of gaze fixations during visual aesthetic perception

RationaleSerotonergic psychedelics are remarkable for their capacity to induce variable yet reproducible modifications to human consciousness The most salient acute effects of these compounds include perceptual alterations, predominantly in the visual domain, yet to date these alterations have been mostly documented only by subjective reports. ObjectivesWe used eye-tracking to quantify the effects of low vs. high doses of psilocybin mushrooms on the eye movements that underlie the exploration of complex visual stimuli, focusing on the particular case of aesthetic perception. ResultsFollowing a double-blind placebo-controlled design under semi-naturalistic conditions, we demonstrated that high doses of psilocybin result in a more local visual exploration of paintings, and thus in a less entropic fixation probability distribution. Participants reported heightened emotional response and state of flow under the high dose condition. ConclusionsThese findings are consistent with an effect of psilocybin on gaze fixation mediated by altered perception of low-level visual information, such as textures, shapes and colors. Our work also highlights the possibility of investigating psychedelics by addressing their effect on behavior under complex naturalistic conditions, which contributes to maintaining subject engagement while also increasing the ecological validity of the findings.

animal behavior and cognition↗