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.
arXiv Preprint Archive
September 26, 2018
A. Viol, Fernanda Palhano-Fontes, Heloisa Onias et al.
A new network metric called geodesic entropy quantifies the Shannon entropy of the distance distribution from each node to all others, capturing the structural role of individual nodes in a network. Applied to functional brain networks of humans in two states of consciousness—ordinary waking and after ingestion of Ayahuasca—the metric distinguished the states. Brain networks under Ayahuasca showed, on average, larger geodesic entropy than those in the ordinary waking state. The authors suggest geodesic entropy is a useful tool for analyzing complex networks and may improve understanding of emergent behaviors such as self-organized criticality.
arXiv Preprint Archive
November 1, 2016
A. Viol, Fernanda Palhano-Fontes, Heloisa Onias et al.
Psychedelic Ayahuasca increases brain network complexity, supporting ancient wisdom about "mind expansion" with modern neuroscience. Brain scans revealed that this Amazonian brew creates more diverse neural connections while strengthening local brain networks. The changes in brain organization showed higher Shannon entropy, indicating more dynamic and flexible thought patterns during the psychedelic experience.