The International Journal of Neuropsychopharmacology
May 17, 2017
Frederic Sampedro, Mario de la Fuente Revenga, Marta Valle et al.
205 citations
A single dose of ayahuasca reduced glutamate+glutamine, creatine, and N-acetylaspartate+N-acetylaspartylglutamate in the posterior cingulate cortex of 16 healthy volunteers, measured post-acutely with magnetic resonance spectroscopy. Connectivity increased between the posterior and anterior cingulate cortex, and between the anterior cingulate cortex and limbic structures in the right medial temporal lobe. Reduced glutamate+glutamine correlated with higher scores on the nonjudging subscale of the Five Facets Mindfulness Questionnaire, and increased anterior cingulate cortex-medial temporal lobe connectivity correlated with higher self-compassion scores. Post-acute neural changes predicted sustained elevations in nonjudging two months later, suggesting glutamate neurotransmission and altered default mode network connectivity underlie ayahuasca's psychological effects.
Molecular Psychiatry
March 31, 2015
Jordi Riba, Marta Valle, Frederic Sampedro et al.
41 citations
Chronic cannabis users, even after a period of abstinence, are more prone to false memories—mistaking events that never occurred for real ones. Using functional magnetic resonance imaging, the study found that abstinent cannabis users showed reduced brain activity in areas critical for memory processing, including the lateral and medial temporal lobe, as well as in parietal and frontal regions involved in attention and monitoring. Cannabis consumption was inversely correlated with medial temporal lobe activity, indicating a specific detriment to episodic memory. These results suggest long-lasting impairments in memory and cognitive control mechanisms that support reality monitoring.
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.