From State-to-Trait Meditation: Reconfiguration of Central Executive and Default Mode Networks.

While brain default mode network (DMN) activation in human subjects has been associated with mind wandering, meditation practice has been found to suppress it and to increase psychological well-being. In addition to DMN activity reduction, experienced meditators (EMs) during meditation practice show an increased connectivity between the DMN and the central executive network (CEN). However, the gradual change between DMN and CEN configuration from pre-meditation, during meditation, and post-meditation is unknown. Here, we investigated the change in DMN and CEN configuration by means of brain activity and functional connectivity (FC) analyses in EMs across three back-to-back functional magnetic resonance imaging (fMRI) scans: pre-meditation baseline (trait), meditation (state), and post-meditation (state-to-trait). Pre-meditation baseline group comparison was also performed between EMs and healthy controls (HCs). Meditation trait was characterized by a significant reduction in activity and FC within DMN and increased anticorrelations between DMN and CEN. Conversely, meditation state and meditation state-to-trait periods showed increased activity and FC within the DMN and between DMN and CEN. However, the latter anticorrelations were only present in EMs with limited practice. The interactions between networks during these states by means of positive diametric activity (PDA) of the fractional amplitude of low-frequency fluctuations (fALFFs) defined as [Formula: see text] revealed no trait differences but significant increases during meditation state that persisted in meditation state-to-trait. The gradual reconfiguration in DMN and CEN suggest a neural mechanism by which the CEN negatively regulates the DMN and is probably responsible for the long-term trait changes seen in meditators and reported psychological well-being.

Psychopharmacologic analysis of an alleged oneirogenic plant: Calea zacatechichi.

Calea zacatechichi is a plant used by the Chontal Indians of Mexico to obtain divinatory messages during dreaming. At human doses, organic extracts of the plant produce the EEG and behavioral signs of somnolence and induce light sleep in cats. Large doses elicit salivation, ataxia, retching and occasional vomiting. The effects of the plant upon cingulum discharge frequency were significantly different from hallucinogenic-dissociative drugs (ketamine, quipazine, phencyclidine and SKF-10047). In human healthy volunteers, low doses of the extracts administered in a double-blind design against placebo increased reaction time and time-lapse estimation. A controlled nap sleep study in the same volunteers showed that Calea extracts increased the superficial stages of sleep and the number of spontaneous awakenings. The subjective reports of dreams were significantly higher than both placebo and diazepam, indicating an increase in hypnagogic imagery occurring during superficial sleep stages.

Ethnopharmacology of ska María Pastora (Salvia divinorum, Epling and Játiva-M.).

Salvia divinorum is a perennial labiate used for curing and divination by the Mazatec Indians of Oaxaca, Mexico. The psychotropic effects the plant produces are compared to those of the other hallucinogens employed by the Mazatecs, the morning glory, Rivea corymbosa L., Hallier f. and the psilocybin-containing mushrooms. A discussion of the role of ska María Pastora in the native "pharmacopeia" is based on previous reports and fieldwork by the authors, with a Mazatec shaman.