Shannon entropy of brain functional complex networks under the influence of the psychedelic Ayahuasca

TL;DR

This study analyzes how Ayahuasca affects brain network entropy and connectivity, supporting the entropic brain hypothesis by showing increased Shannon entropy and altered network integration during altered states of consciousness.

Contribution

It provides empirical evidence of increased Shannon entropy in brain networks under Ayahuasca, linking complex network analysis with psychedelic-induced brain state changes.

Findings

Increased Shannon entropy of brain networks after Ayahuasca ingestion

Altered local and global network integration patterns

Results support the entropic brain hypothesis

Abstract

The entropic brain hypothesis holds that the key facts concerning psychedelics are partially explained in terms of increased entropy of the brain's functional connectivity. Ayahuasca is a psychedelic beverage of Amazonian indigenous origin with legal status in Brazil in religious and scientific settings. In this context, we use tools and concepts from the theory of complex networks to analyze resting state fMRI data of the brains of human subjects under two distinct conditions: (i) under ordinary waking state and (ii) in an altered state of consciousness induced by ingestion of Ayahuasca. We report an increase in the Shannon entropy of the degree distribution of the networks subsequent to Ayahuasca ingestion. We also find increased local and decreased global network integration. Our results are broadly consistent with the entropic brain hypothesis. Finally, we discuss our findings in the context of descriptions of "mind-expansion" frequently seen in self-reports of users of psychedelic drugs.