Functional connectivity
Do psychedelics make brain networks talk to each other more?
Open access · cc by · source: Europe PMC
Psilocybin made many normally separate brain networks fluctuate together more, whereas MDMA, with similarly intense subjective effects, changed almost none of these links.
Study at a glance
- Design
- Human experiment — New analysis of two within-subject placebo-controlled fMRI studies (IV psilocybin; oral MDMA), comparing between-network coupling of 13 template resting-state networks under drug vs placebo.
- N
- 15 volunteers in the psilocybin study; 13 analysed in the MDMA study after excluding 12 of the original 25 (low effect intensity or head motion).
- Population
- Healthy adult volunteers with previous experience of the drug
- Outcome
- Between-resting-state-network functional connectivity (regression coupling strength) under drug versus placebo
Structured fields used in claim comparison tables when every cited study has a complete layer.
Key findings
Under psilocybin, dozens of network pairs showed stronger coupling, including links between the default mode network and visual or attention networks, and between higher-order frontoparietal networks. Coupling fell only between the three visual networks and the sensorimotor network. Under MDMA just one pair changed (an anterior default-mode/executive-control link, which also rose under psilocybin), even though both drugs were rated as similarly intense. The authors interpret this as a 'flattening' of the brain's attractor landscape, letting it move more freely between states.
Methodology
The authors re-analysed resting-state fMRI from two earlier studies in which healthy volunteers were scanned once on a drug and once on placebo: 15 people given intravenous psilocybin and 13 given oral MDMA. They took thirteen standard brain networks (visual, auditory, sensorimotor, default mode, frontoparietal, attention and others) from a published template, extracted each network's activity time course, and measured how strongly every pair of networks was coupled. Drug and placebo coupling were compared pair by pair with correction for multiple comparisons.
Limitations
The two drugs came from separate studies using different scanners, routes of administration and participants, so the authors stress this is not a formal head-to-head comparison. Head motion increased under both drugs and correlated with the coupling change for several psilocybin pairs, including all the visual-sensorimotor decreases, so those results may partly reflect movement. Samples were small, mostly male in the psilocybin study, and made up of experienced drug users. The attractor-landscape and consciousness interpretations are theoretical and were not directly tested.
How this study connects
Role on claims
Each row is a claim on a concept or method page where this paper supports, challenges, or qualifies the statement. Roles are hand-checked — not a model guess.
Not yet placed on a claim. This paper has study layers, but no concept page yet cites it as support, challenge, or qualifier.
Related papers in this topic
Same topic cluster — not a recommendation engine.