Scientific Reports
August 1, 2017
Aline Viol, Fernanda Palhano-Fontes, Heloisa Onias et al.
154 citations
The entropic brain hypothesis suggests that psychedelic experiences arise from increased randomness in the brain's functional connectivity. Analyzing resting-state fMRI data from human subjects before and after ingesting ayahuasca, a psychedelic beverage used in Amazonian religious and scientific contexts, researchers found that the Shannon entropy of the brain's degree distribution increased, indicating greater disorder in network connections. Local integration within brain networks increased while global integration decreased. These findings align with the entropic brain hypothesis and relate to users' reports of 'mind-expansion.'
Entropy
January 30, 2019
Aline Viol, Fernanda Palhano-Fontes, Heloisa Onias et al.
37 citations
A new network metric, geodesic entropy, measures the Shannon entropy of distances from one node to all others in a network, characterizing how much influence a node has based on the overall network structure. Applied to resting-state functional brain networks of humans, the metric differentiates ordinary consciousness from the altered state induced by Ayahuasca ingestion. On average, functional networks from subjects in the altered state show larger geodesic entropy than those in the ordinary state, suggesting the metric can reveal differences in brain network organization across states of consciousness.
Journal of Physics Complexity
March 1, 2023
Aline Viol, G. M. Viswanathan, Oleksandra Soldatkina et al.
4 citations
The physical basis of consciousness is a central open question in science. This work compares resting-state functional brain networks of individuals before and after ingesting the psychedelic brew Ayahuasca. Using a measure called pairwise information parity, which quantifies statistical symmetries between brain region connections across the entire network, the authors found an increase in average information parity under psychedelic influence. Notably, information parity between regions of the limbic system and frontal cortex was consistently higher for all individuals while under the influence. These findings suggest that the resemblance of statistical influences between pairs of brain region activities tends to increase under Ayahuasca, possibly as a mechanism to maintain network functional resilience.
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.
arXiv Preprint Archive
July 28, 2022
Aline Viol, Gandhi M. Viswanathan, Oleksandra Soldatkina et al.
The physical basis of consciousness remains an open question. Using complex network theory, the study compared resting-state functional brain networks of individuals before and after ingesting the psychedelic brew Ayahuasca. The researchers calculated pairwise information parity to quantify statistical symmetries between brain region connectivity across the entire network. They detected an increase in average information parity in brain networks under psychedelic influence. Notably, information parity between regions of the limbic system and frontal cortex was consistently higher for all individuals while under the influence.