An exploratory persistent-homology analysis of resting-state fMRI functional connectivity under Ayahuasca
Chaos Solitons & Fractals May 30, 2026 Tales Ramos Monteiro Dos Santos, Dráulio B. Araújo, Helcio Felippe et al.
Psychedelic states can help researchers understand how the brain reorganizes at a large scale. In nine people scanned before and after taking ayahuasca, topological data analysis of resting-state fMRI connectivity showed a nominal decrease in persistent entropy of H2 features—a measure of higher-dimensional topological structure—that did not survive correction for multiple comparisons and was not reproduced with signed correlations. Exploratory analyses of signal complexity found descriptive but non-significant increases. These preliminary, hypothesis-generating results highlight persistent homology as a potential framework for studying psychedelic-related brain changes, but replication in larger placebo-controlled studies is needed.