Not in the drug, not in the brain: Causality in psychedelic experiences from an enactive perspective

Meditating on psychedelics. A randomized placebo-controlled study of DMT and harmine in a mindfulness retreat

BACKGROUND

In recent years, both meditation and psychedelics have attracted rapidly increasing scientific interest. While the current state of evidence suggests the promising potential of psychedelics, such as psilocybin, to enhance meditative training, it remains equivocal whether these effects are specifically bound to psilocybin or if other classical psychedelics might show synergistic effects with meditation practice. One particularly promising candidate is N,N-dimethyltryptamine (DMT), an active ingredient of ayahuasca.

AIM

This study aims to investigate the effect of the psychedelic substance DMT, combined with the monoamine oxidase inhibitor harmine (DMT-harmine), on meditative states, compared to meditation with a placebo.

METHOD

Forty experienced meditators (18 females and 22 males) participated in a double-blind, placebo-controlled study over a 3-day meditation retreat, receiving either placebo or DMT-harmine. Participants' levels of mindfulness, compassion, insight, and transcendence were assessed before, during, and after the meditation group retreat, using psychometric questionnaires.

RESULTS

Compared to meditation with a placebo, meditators who received DMT and harmine self-attributed greater levels of mystical-type experiences, non-dual awareness, and emotional breakthrough during the acute substance effects and, when corrected for baseline differences, greater psychological insight 1 day later. Mindfulness and compassion were not significantly different in the DMT-harmine group compared to placebo. At 1-month follow-up, the meditators who received DMT and harmine rated their experience as significantly more personally meaningful, spiritually significant, and well-being-enhancing than the meditators who received placebo.

CONCLUSION

Investigating the impact of DMT-harmine on meditators in a naturalistic mindfulness group retreat, this placebo-controlled study highlights the specific effects of psychedelics during meditation.

TRIAL REGISTRATION

ClinicalTrials.gov identifier NCT05780216.

Co-administration of midazolam and psilocybin: differential effects on subjective quality versus memory of the psychedelic experience

Aspects of the acute experience induced by the serotonergic psychedelic psilocybin predict symptomatic relief in multiple psychiatric disorders and improved well-being in healthy participants, but whether these therapeutic effects are immediate or are based on memories of the experience is unclear. To examine this, we co-administered psilocybin (25 mg) with the amnestic benzodiazepine midazolam in 8 healthy participants and assayed the subjective quality of, and memory for, the dosing-day experience. We identified a midazolam dose that allowed a conscious psychedelic experience to occur while partially impairing memory for the experience. Furthermore, midazolam dose and memory impairment tended to associate inversely with salience, insight, and well-being induced by psilocybin. These data suggest a role for memory in therapeutically relevant behavioral effects occasioned by psilocybin. Because midazolam blocks memory by blocking cortical neural plasticity, it may also be useful for evaluating the contribution of the pro-neuroplastic properties of psychedelics to their therapeutic activity.

Psilocybin enhances insightfulness in meditation: a perspective on the global topology of brain imaging during meditation

In this study, for the first time, we explored a dataset of functional magnetic resonance images collected during focused attention and open monitoring meditation before and after a five-day psilocybin-assisted meditation retreat using a recently established approach, based on the Mapper algorithm from topological data analysis. After generating subject-specific maps for two groups (psilocybin vs. placebo, 18 subjects/group) of experienced meditators, organizational principles were uncovered using graph topological tools, including the optimal transport (OT) distance, a geometrically rich measure of similarity between brain activity patterns. This revealed characteristics of the topology (i.e. shape) in space (i.e. abstract space of voxels) and time dimension of whole-brain activity patterns during different styles of meditation and psilocybin-induced alterations. Most interestingly, we found that (psilocybin-induced) positive derealization, which fosters insightfulness specifically when accompanied by enhanced open-monitoring meditation, was linked to the OT distance between open-monitoring and resting state. Our findings suggest that enhanced meta-awareness through meditation practice in experienced meditators combined with potential psilocybin-induced positive alterations in perception mediate insightfulness. Together, these findings provide a novel perspective on meditation and psychedelics that may reveal potential novel brain markers for positive synergistic effects between mindfulness practices and psilocybin.

The Fundamental Tension in Integrated Information Theory 4.0's Realist Idealism

Integrated Information Theory (IIT) is currently one of the most influential scientific theories of consciousness. Here, we focus specifically on a metaphysical aspect of the theory's most recent version (IIT 4.0), what we may call its idealistic ontology, and its tension with a kind of realism about the external world that IIT also endorses. IIT 4.0 openly rejects the mainstream view that consciousness is generated by the brain, positing instead that consciousness is ontologically primary while the physical domain is just "operational". However, this philosophical position is presently underdeveloped and is not rigorously formulated in IIT, potentially leading to many misinterpretations and undermining its overall explanatory power. In the present paper we aim to address this issue. We argue that IIT's idealistic ontology should be understood as a specific combination of phenomenal primitivism, reductionism regarding Φ-structures and complexes, and eliminativism about non-conscious physical entities. Having clarified this, we then focus on the problematic tension between IIT's idealistic ontology and its simultaneous endorsement of realism, according to which there is some kind of external reality independent of our minds. After refuting three potential solutions to this theoretical tension, we propose the most plausible alternative: understanding IIT's realism as an assertion of the existence of other experiences beyond one's own, what we call a non-solipsistic idealist realism. We end with concluding remarks and future research avenues.