Conference Agenda

Altered states of consciousness are valuable tools for studying consciousness. By examining changes in brain activity during states such as anesthesia, where consciousness is lost, or psychedelic experiences, where perception and cognition are profoundly altered, we deepen our understanding of the mechanisms underlying conscious experience.

In this analysis, we ask if cognitive states at rest can be decoded from fMRI BOLD signal and how DMT influences this spontaneous brain activity. To investigate this, we leveraged the NeuroSynth database of meta-analytic cognitive maps to extract cognitive matching scores from resting-state fMRI data in participants before and after DMT administration. Cognitive matching involves decoding cognitive processes from an fMRI time series by spatially correlating the participants’ brain signals with 123 cognitive term-associated NeuroSynth maps.

Our first analysis identified the highest absolute correlation value at each time point, averaging them to obtain a cognitive matching score. This score indicates how easily cognition is decoded from the fMRI signal. This score was significantly reduced in the DMT state. Next, we examined which specific NeuroSynth terms exhibited significant alterations in matching quality between conditions. Using a linear regression model that accounted for motion, we identified 35 terms—including imagery, insight, social cognition, and salience—showing significantly different cognitive matching scores. Lastly, we explored the dynamics of these terms under DMT, revealing fluctuating cognitive states, such as social cognition shifting from high correlation to anticorrelation over time.

These findings suggest that DMT reorganizes spontaneous cognition in distinct ways, enhancing our understanding of resting-state brain dynamics and altered consciousness.

Just as a flute's design shapes its pitch and timbre, brain function is constrained by its anatomy (see Luppi et al. 2024 for review). Converging evidence suggests that the relationship between the brain’s structure and function varies across cognitive states, including altered states of consciousness. Recent work has shown that anesthesia strengthens structure-function coupling (Luppi et al. 2023), while psychedelics such as lysergic acid diethylamide (LSD) induces flexibility and independence from the anatomical structure (Atasoy et al. 2017). Because previous studies have largely examined brain function using fMRI, our understanding of the changes in structure-function coupling during different states of consciousness remains incomplete. Here, we analyzed magnetoencephalography (MEG) data, alongside diffusion-weighted imaging to assess changes in structure-function coupling induced by LSD. Using a consensus structural graph from 56 subjects (Preti & Van de Ville, 2019), we examined MEG (N=17) recorded while subjects are under LSD and placebo (Carhart-Harris et al., 2016). We applied dSPM for source localization and used Graph Signal Processing (Ortega et al. 2018) to map functional activity onto the structural graph. Our results suggest LSD reduces graph power, a trend observed across all spatial harmonics. This observation aligns with reports LSD induces broadband desynchronization (Muthukumarasamy et al. 2013). Our source-space analysis captures how LSD alters structure-function coupling with high spatial and temporal resolution. Overall, our findings provide novel insights into how neural dynamics under psychedelics are shaped by the structural properties of the brain and provide electrophysiological features that may underlie the phenomenological changes induced by LSD.

Psychedelics, especially ayahuasca, are known to produce significant changes in consciousness and self-awareness. Recent research has mainly concentrated on ayahuasca’s antidepressant effects, linking changes in self-awareness to therapeutic outcomes. However, there is limited research exploring how factors such as an individual’s mindset (set), environment (setting), the substance itself, and sociodemographic characteristics interact to shape self-awareness changes during ceremonial use. In our study, we recruited 755 participants attending ayahuasca rituals and gathered data through surveys administered before and after the ceremonies. We conducted hierarchical regressions on several self-alteration outcomes, using tools such as the Ego Dissolution Inventory, the Altered States of Consciousness Rating Scale, and the Mystical Experience Questionnaire. Predictors included sociodemographic characteristics, substance-related variables, set, and features of the setting. Some strong predictors of self-alteration were in line with previous findings in the literature such as dose ingested, spiritual/metaphysical beliefs, and presence of caretakers. Other strong predictors were never indicated as impactful predictors before, such as interoceptive awareness, aberrant salience, other substances used during the ceremony, and biological sex. Thus, findings from this study contribute to the psychedelic research field by throwing light on new and previously indicated interactions between different contextual factors during psychedelic experiences and their role in self-alteration processes.

Classical serotonergic psychedelics show promise in addressing neurodegenerative disorders such as Alzheimer’s disease by modulating pathological brain dynamics. However, the precise neurobiological mechanisms underlying their effects remain elusive. This study introduces a personalized whole-brain model built upon a laminar neural mass framework to elucidate these effects. Using multimodal neuroimaging data from thirty subjects diagnosed with Alzheimer’s disease, we simulate the impact of serotonin 2A receptor activation, characteristic of psychedelics, on cortical dynamics. By modulating the excitability of layer 5 pyramidal neurons, our models reproduce hallmark changes in EEG power spectra observed under psychedelics, including alpha power suppression and gamma power enhancement. These spectral shifts are shown to correlate strongly with the regional distribution of serotonin 2A receptors. Furthermore, simulated EEG reveals increased complexity and entropy, suggesting restored network function. These findings underscore the potential of serotonergic psychedelics to reestablish healthy oscillatory dynamics in the prodromal and early phases of Alzheimer’s disease and offer mechanistic insights into their potential therapeutic effects in neurodegenerative disorders.