Effects of the South American Psychoactive Beverage <i>Ayahuasca </i>on Regional Brain Electrical Activity in Humans: A Functional Neuroimaging Study Using Low-Resolution Electromagnetic Tomography
Neuropsychobiology – January 01, 2004
Source: OpenAlex
Summary
Ayahuasca, a psychedelic tea, significantly alters brain activity and subjective experiences. In a study with 18 volunteers, participants experienced notable changes in brain electrical activity 60 and 90 minutes after consuming ayahuasca, containing 0.85 mg DMT per kg body weight. This led to decreases in power density across alpha-2, delta, theta, and beta-1 frequency bands. Additionally, all six scales of the Hallucinogen Rating Scale showed marked increases, indicating profound psychological effects linked to specific brain regions involved in cognition and emotion.
Abstract
<i>Ayahuasca,</i> a South American psychotropic plant tea obtained from <i>Banisteriopsis caapi</i> and <i>Psychotria viridis</i>, combines monoamine oxidase-inhibiting β-carboline alkaloids with N,N-dimethyltryptamine (DMT), a psychedelic agent showing 5-HT<sub>2A</sub> agonist activity. In a clinical research setting, <i>ayahuasca</i> has demonstrated a combined stimulatory and psychedelic effect profile, as measured by subjective effect self-assessment instruments and dose-dependent changes in spontaneous brain electrical activity, which parallel the time course of subjective effects. In the present study, the spatial distribution of <i>ayahuasca</i>-induced changes in brain electrical activity was investigated by means of low-resolution electromagnetic tomography (LORETA). Electroencephalography recordings were obtained from 18 volunteers after the administration of a dose of encapsulated freeze-dried <i>ayahuasca</i> containing 0.85 mg DMT/kg body weight and placebo. The intracerebral power density distribution was computed with LORETA from spectrally analyzed data, and subjective effects were measured by means of the Hallucinogen Rating Scale (HRS). Statistically significant differences compared to placebo were observed for LORETA power 60 and 90 min after dosing, together with increases in all six scales of the HRS. <i>Ayahuasca</i> decreased power density in the alpha-2, delta, theta and beta-1 frequency bands. Power decreases in the delta, alpha-2 and beta-1 bands were found predominantly over the temporo-parieto-occipital junction, whereas theta power was reduced in the temporomedial cortex and in frontomedial regions. The present results suggest the involvement of unimodal and heteromodal association cortex and limbic structures in the psychological effects elicited by <i>ayahuasca</i>.