Systematic review · 2026
A scoping review of how psychedelics affect thalamus-to-cortex brain circuits
- Original title
- Psychedelics and the thalamocortical system: A scoping review.
- Authors
- Villalba S, Christensen AM, Di Costanzo L, et al.
- Journal
- Pharmacology, biochemistry, and behavior, 2026
- Molecules
- Ibogaine, Other
- Conditions
- Depression, Substance use disorder, PTSD, OCD, End-of-life distress, Other
- Evidence grade
- Very low
- Source
- Read the original paper
The question
What does the existing research say about how psychedelic drugs affect the thalamocortical system, the brain circuit that links the thalamus (a relay hub deep in the brain) with the outer cortex?
What they did
The authors carried out a scoping review, a structured survey of the published literature, following PRISMA reporting methods. They gathered both preclinical (animal and laboratory) and clinical (human) studies on compounds with possible clinical use: NMDA receptor blockers, serotonin 2A receptor activators, and mixed-action compounds such as iboga alkaloids. They then summarized what these studies reported about thalamocortical activity and connectivity.
What they found
The review reports that psychedelic compounds change connectivity between the thalamus and the cortex, and argues these changes may help explain the altered state of consciousness these drugs produce. The authors also note that conditions such as depression, schizophrenia, bipolar disorder and autism have been linked to differences in the same thalamocortical circuits. The abstract does not give any specific numbers, effect sizes, or counts of included studies.
The fine print
This is a narrative synthesis, not a statistical pooling of results, and it mixes animal studies with human studies, so conclusions cannot be applied directly to patients. The abstract reports no sample sizes, no list of included studies and no quality appraisal. Brain connectivity is a surrogate measure: changes in a brain scan are not the same as improvement in symptoms. This summary is based on the abstract alone.
What it means
Researchers are building a case that psychedelics act partly by shifting communication between the thalamus and the cortex, but this review maps out ideas and existing findings rather than testing whether those brain changes translate into better clinical outcomes.
Evidence grade: Very low. A scoping review that pools animal and human findings, reports no pooled numbers or participant counts, and does not formally assess study quality.
This summary is based on the study’s published abstract.