Synergistic, Multi-level Understanding of Psychedelics: Three Systematic Reviews and Meta-analyses of Their Pharmacology, Neuroimaging and Phenomenology

Abstract

Serotonergic psychedelics induce altered states of consciousness and have shown potential in treating a variety of neuropsychiatric disorders, including depression and addiction. Yet their modes of action are currently not fully understood. Here, we provide three systematic reviews and meta-analyses of three hierarchical levels relevant to the effects of psychedelics, i.e., 1) their molecular pharmacology, 2) whole-brain neuroimaging and 3) subjective experience (phenomenology). Our meta-analyses link each of the classic psychedelics (DMT, LSD, and psilocybin) to specific neural fingerprints at each level of this tripartite hierarchy. The results show a highly non-linear relationship between these fingerprints. Overall, the results point to the need for standardising experimental procedures and analysis techniques, as well as for more research on the emergence between different levels of psychedelic effects. Future work could use our tripartite hierarchy framework to investigate the dose-dependent effects of different psychedelics in the same participants.

Breathwork-Induced Psychedelic Experiences Modulate Neural Dynamics

“…Although arguably much more informative than likert scale questionnaires, TET remains a reductionist approach to the study of subjective experience. While one phenomenological cluster yielded similarities to positive psychedelic phenomenology (Hirschfield & Schmidt, 2021) and neural markers of psychedelics (Schartner et al, 2017;Timmermann et al, 2019), there are most likely a variety of phenomenological distinctions between the two states, much like the phenomenological nuances between different psychedelics (Shinozuka et al, 2023). It may thus be more useful to characterise this breathwork modality, along with psychedelics, as a 'high-arousal' ASC, rather than 'high-relaxation', as has been previously suggested as a useful taxonomic category for Eastern spiritual practices (Amihai & Kozhenivkov, 2014;.…”