![]() DMT is usually rapidly metabolized by monoamine oxidase (MAO), but the presence of MAOI allows DMT to cross the blood-brain barrier and to exert its effects 19, 20, 21, 22, 23, 24. The beverage is typically obtained by decoction of two plants from the Amazonian flora: the bush Psychotria viridis, that contains DMT, and the liana Banisteriopsis caapi, that contains MAOIs 18. It contains the powerful psychedelic N, N- dimethyltryptamine (DMT), together with harmala alkaloids that are known to be monoamine oxidase inhibitors (MAOIs). considering the entire brain.Īyahuasca is a beverage of Amazonian indigenous origin and has legal status in Brazil in religious and scientific settings 17. This is the first time that the entropy of the functional networks of the human brain has been directly measured in altered states of consciousness on a global scale, i.e. Specifically, we analyze fMRI functional connectivity of human subjects before and after they ingest the psychoactive brew Ayahuasca and report an increase in the Shannon entropy. Here we directly measure increases in entropy associated with the functional connectivity of the whole brain under the influence of a psychedelic. 16 have very recently reported evidence of increases in specific measures of entropy, the former with LSD and the latter with LSD, psilocybin and ketamine. They inferred an increase in the entropy of the functional connectivity in some regions of the brain, by studying the temporal evolution (i.e., dynamics) of the connectivity graphs. 14, who reported a larger repertoire of brain dynamical states during the psychedelic experience with psilocybin. Perhaps the most convincing evidence supporting the hypothesis thus far has come from the study undertaken by Tagliazucchi et al. found that after administration of the psychedelic psilocybin, the brain’s functional patterns undergo a dramatic change characterized by the appearance of many transient low-stability structures 13. have reported complex spatiotemporal cortical activation pattern during anesthesia with ketamine, which can induce vivid experiences (“ketamine dreams”) 12. Although until recently the entropy of the brain had never been directly measured, the entropic brain hypothesis is empirically supported by several recent studies. proposed a hypothesis known as the entropic brain, which holds that the stylized facts concerning altered states of consciousness induced by psychedelics can be partially explained in terms of higher entropy of the brain’s functional connectivity 11. During the last few years, new neuroimaging techniques, such as functional magnetic resonance imaging (fMRI) 1, 2, have allowed noninvasive investigation of global brain activity in a variety of conditions, e.g., under anaesthesia, sleep, coma, and in altered states of consciousness induced by psychedelic drugs 3, 4, 5, 6, 7, 8, 9, 10. Relatively little is known about how exactly psychedelics act on human functional brain networks. Finally, we discuss our findings in the context of descriptions of “mind-expansion” frequently seen in self-reports of users of psychedelic drugs. Our results are broadly consistent with the entropic brain hypothesis. We also find increased local and decreased global network integration. We report an increase in the Shannon entropy of the degree distribution of the networks subsequent to Ayahuasca ingestion. 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. Ayahuasca is a psychedelic beverage of Amazonian indigenous origin with legal status in Brazil in religious and scientific settings. 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.
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