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New World Tryptamine Hallucinogens and the Neuroscience of Ayahuasca.

Dennis J. Mckenna, Jordi Riba

Current Topics in Behavioral Neurosciences 2018 DOI: 10.1007/7854_2016_472 (opens in new tab)

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Study at a glance

AI-extracted from the abstract
Characteristics Review with original neuroimaging and neurophysiological data Peer reviewed
Intervention Ayahuasca
Topics Philosophy of mind Ayahuasca
Keywords Ayahuasca research Amazonian brew Tryptamine compounds Hallucinogens Brain chemistry Neural pathways Serotonin systems Brain regions Neuroimaging Pharmacological studies Mood Self-awareness Emotion Mental well-being Therapeutic potential Altering perception Understanding consciousness
Citations 67
Key findings Ayahuasca temporarily modifies the ordinary flow of information within the brain by reducing top-down constraints and facilitating bottom-up information transfer, disrupting neural hierarchies.

Abstract

New World indigenous peoples are noted for their sophisticated use of psychedelic plants in shamanic and ethnomedical practices. The use of psychedelic plant preparations among New World tribes is far more prevalent than in the Old World. Yet, although these preparations are botanically diverse, almost all are chemically similar in that their active principles are tryptamine derivatives, either DMT or related constituents. Part 1 of this paper provides an ethnopharmacological overview of the major tryptamine-containing New World hallucinogens. Part 2 focuses on ayahuasca and its effects on the human brain. Using complementary neurophysiological and neuroimaging techniques, we have identified brain areas involved in the cognitive effects induced by this complex botanical preparation. Initial SPECT data showed that ayahuasca modulated activity in higher order association areas of the brain. Increased blood perfusion was observed mainly in anterior brain regions encompassing the frontomedial and anterior cingulate cortices of the frontal lobes, and in the medial regions of the temporal lobes. On the other hand, applying spectral analysis and source location techniques to cortical electrical signals, we found changes in neuronal activity that predominated in more posterior sensory-selective areas of the brain. Now, using functional connectivity analysis of brain oscillations we have been able to reconcile these seemingly contradictory findings. By measuring transfer entropy, a metric based on information theory, we have shown that ayahuasca temporarily modifies the ordinary flow of information within the brain. We propose a model in which ayahuasca reduces top-down constraints and facilitates bottom-up information transfer. By simultaneously enhancing endogenous cortical excitability and reducing higher-order cognitive control, ayahuasca temporarily disrupts neural hierarchies allowing inner exploration and a new outlook on reality.

Comparable studies

Other experimental studies on ayahuasca, most cited first.

Study Year Design Participants
Seeing with the eyes shut: Neural basis of enhanced imagery following ayahuasca ingestion Human participants (number not stated) 2011 Within-subjects experimental study
Ayahuasca enhances creative divergent thinking while decreasing conventional convergent thinking Participants at spiritual ayahuasca workshops 2016 Within-subjects experimental study n = 26
Metabolism and disposition of N,N‐dimethyltryptamine and harmala alkaloids after oral administration of ayahuasca Healthy male volunteers 2012 Observational pharmacokinetic study n = 10
Stability Evaluation of DMT and Harmala Alkaloids in Ayahuasca Tea Samples Ayahuasca tea samples 2020 Experimental study
Ayahoasca: an experimental psychosis that mirrors the transmethylation hypothesis of schizophrenia. Healthy subjects 1999 Experimental study

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Philosophy of mind Ayahuasca DMT Shamanism