Behavioural Investigations of Psilocybin in Animals 1962-2021: A Scoping Review
Bibliographic record
Abstract
Abstract Background and Aims Psilocybin is a psychedelic drug that may hold promise for a wide range of human health conditions, yet the identification of therapeutic processes and mechanisms of action remains exploratory. We conducted a scoping review on pre-clinical behavioural investigations of psilocybin in non-human animals to help determine the behavioural effects of psilocybin in non-human animals, to identify studies completed, behavioural tests employed, and what dosing modalities had been studied. Methods A librarian-conducted literature search was performed using predefined key terms and search criteria and additional searching was conducted by reviewers, using electronic databases, grey literature sources, and reference lists of relevant articles or reviews. The final search updated occurred in October, 2021. Studies were reviewed, screened and selected against an a priori protocol using Covidence software by multiple reviewers with results plotted across the Research Domains Criteria construct. Results From 4124 records identified by database searching, 260 publications were subjected to full-text review with 77 studies included in this scoping review, published between 1962-2021. The preponderance of studies (n=64) investigated behavioural outcomes in rodents. Only 43 studies (55.8%) reported on housing conditions, and seventeen studies (22.1%) failed to report sample size. All studies reported behavioural outcomes following drug administration, with fifty-one studies (66.2%) using psilocybin, thirty studies (42.9%) psilocin, four studies (5.2%) administering whole mushroom extracts (WME), and a further eight studies investigating both psilocybin and psilocin and one study reporting the effects of both psilocin and WME. One hundred and thirty distinct behavioural investigations using fifty different behavioral paradigms were identified. Few adverse events were reported, and even exceedingly high doses were apparently well tolerated. Conclusion With seventy-seven publications spanning close to sixty years, there is huge variation in study design and quality. Overall psilocybin presents a unique and strong safety profile with no evidence of biological toxicity, is characterized by unique time and dose-dependent effects, and its pattern of drug action is significantly context and training-sensitive. Data suggest putative effects of psilocybin include acute arousal, dose-dependent sedation, reductions in fear conditioning at low doses, reduced aggression, improved valence, acute disruption of working memory, the rescuing of deficits from chronic stress, and improved learning when combined with repeated environmental exposure after resolution of drug effect.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.010 | 0.034 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.005 | 0.004 |
| Bibliometrics | 0.019 | 0.016 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.004 | 0.004 |
| Open science | 0.002 | 0.002 |
| Research integrity | 0.003 | 0.001 |
| Insufficient payload (model declined to judge) | 0.008 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".