European Neuropsychopharmacology
March 26, 2016
Marta Valle, Ana Maqueda, Mireia Rabella et al.
175 citations
Ayahuasca, a psychoactive Amazonian tea, contains DMT and other compounds. In a double-blind, placebo-controlled study with 12 experienced users, ayahuasca reduced brain oscillations in delta, theta, and alpha frequency bands. The intensity of visual imagery correlated inversely with alpha-band current density in parietal and occipital cortex. Pretreatment with the 5-HT2A antagonist ketanserin blocked these neurophysiological changes, weakened the correlation between alpha activity and visual effects, and reduced subjective intensity. These results indicate that activation of the 5-HT2A receptor is central to ayahuasca's neurophysiological and visual effects in humans, despite the tea's chemical complexity.
The International Journal of Neuropsychopharmacology
March 29, 2015
Joan Francesc Alonso, Sergio Romero, Miguel Ángel Mañanas et al.
105 citations
Ayahuasca, a psychedelic containing the serotonergic 5-HT2A agonist N,N-dimethyltryptamine, temporarily disrupts neural hierarchies in the human brain by reducing top-down control and increasing bottom-up information transfer. In ten healthy male volunteers with prior psychedelic experience, transfer entropy analysis of brain oscillations showed that frontal sources decreased their influence over central, parietal, and occipital sites, while posterior sources increased their influence over anterior locations. Decreases in anterior-to-posterior transfer entropy correlated with the intensity of subjective effects, and the imbalance between anterior-to-posterior and posterior-to-anterior transfer entropy correlated with the degree of incapacitation experienced.
The international journal of neuropsychopharmacology
January 12, 2022
Genís Ona, Frederic Sampedro, Sergio Romero et al.
17 citations
Kappa opioid receptor (KOR) agonists like salvinorin-A produce psychotomimetic effects through largely unknown mechanisms. In a double-blind, crossover, randomized, placebo-controlled study, acute administration of salvinorin-A increased delta and gamma brain waves while decreasing alpha waves, as measured by electroencephalography. Single-photon emission computed tomography revealed significant decreases in regional cerebral blood flow across frontal, temporal, parietal, and occipital cortices, with increases in the medial temporal lobe, amygdala, hippocampal gyrus, and cerebellum. Subjective effects resembled other psychotomimetic drugs but were distinctly dissociative, with no dysphoria reported. KOR agonism by salvinorin-A induces dramatic psychotomimetic effects alongside generalized reductions in cortical blood flow and electrical activity.