Neuroimaging & Brain MeasuresAyahuasca

Seeing with the eyes shut: Neural basis of enhanced imagery following ayahuasca ingestion

Using fMRI during a closed‑eyes imagery task, the study shows Ayahuasca markedly increases activation across occipital, temporal and frontal cortices—primary visual cortex activation reached levels comparable to seeing real images and BA30, BA37 and BA10 (memory, contextual association and prospective imagination) were potentiated. These neural effects correlated with individual measures of perceptual change, suggesting Ayahuasca amplifies internally generated imagery to a degree that confers a sense of reality to visionary experiences.

Authors

  • Jamie Hallak
  • Sidarta Ribeiro
  • Jaime Crippa

Published

Human Brain Mapping
individual Study

Abstract

The hallucinogenic brew Ayahuasca, a rich source of serotonergic agonists and reuptake inhibitors, has been used for ages by Amazonian populations during religious ceremonies. Among all perceptual changes induced by Ayahuasca, the most remarkable are vivid “seeings.” During such seeings, users report potent imagery. Using functional magnetic resonance imaging during a closed‐eyes imagery task, we found that Ayahuasca produces a robust increase in the activation of several occipital, temporal, and frontal areas. In the primary visual area, the effect was comparable in magnitude to the activation levels of natural image with the eyes open. Importantly, this effect was specifically correlated with the occurrence of individual perceptual changes measured by psychiatric scales. The activity of cortical areas BA30 and BA37, known to be involved with episodic memory and the processing of contextual associations, was also potentiated by Ayahuasca intake during imagery. Finally, we detected a positive modulation by Ayahuasca of BA 10, a frontal area involved with intentional prospective imagination, working memory and the processing of information from internal sources. Therefore, our results indicate that Ayahuasca seeings stem from the activation of an extensive network generally involved with vision, memory, and intention. By boosting the intensity of recalled images to the same level of natural image, Ayahuasca lends a status of reality to inner experiences. It is therefore understandable why Ayahuasca was culturally selected over many centuries by rain forest shamans to facilitate mystical revelations of visual nature. Hum Brain Mapp, 2012. © 2011 Wiley Periodicals, Inc.

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Research Summary of 'Seeing with the eyes shut: Neural basis of enhanced imagery following ayahuasca ingestion'

Introduction

Ayahuasca is a traditional Amazonian brew combining Psychotria viridis (a source of DMT) and Banisteriopsis caapi (b-carbolines that act as monoamine oxidase inhibitors). De Araujo and colleagues frame Ayahuasca's psychopharmacology as a synergistic interaction in which orally inactive DMT becomes psychoactive when MAO is inhibited, producing autonomic and pronounced psychological effects including vivid, internally generated visual experiences commonly called "seeings". Earlier neuroimaging work has shown overlap between brain regions engaged by visual perception and by mental imagery, but the involvement of primary visual cortex (V1, Brodmann area 17) in imagery remains controversial, and the neural basis of Ayahuasca-induced vivid imagery has not been characterised. This study set out to identify brain systems underlying the heightened imagery that accompanies Ayahuasca ingestion. Using BOLD (blood oxygenation level dependent) functional MRI, the investigators compared brain activity during three conditions—viewing natural images, closed‑eyes imagery of those images, and viewing scrambled versions of the images—before and after oral Ayahuasca. They sought to determine which visual, temporal and frontal areas are potentiated during imagery after ingestion, whether primary visual cortex is engaged, and how neural changes relate to measured psychological effects.

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References (4)

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