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J. Hallak

The Psychedelic State Induced by Ayahuasca Modulates the Activity and Connectivity of the Default Mode Network

February 18, 2015 / Ayahuasca, Neuroscience, Other subjects, Papers, Psychology, Psychopharmacology, Publications / By / , , , , , ,

Abstract

The experiences induced by psychedelics share a wide variety of subjective features, related to the complex changes in perception and cognition induced by this class of drugs. A remarkable increase in introspection is at the core of these altered states of consciousness. Self-oriented mental activity has been consistently linked to the Default Mode Network (DMN), a set of brain regions more active during rest than during the execution of a goal-directed task. Here we used fMRI technique to inspect the DMN during the psychedelic state induced by Ayahuasca in ten experienced subjects. Ayahuasca is a potion traditionally used by Amazonian Amerindians composed by a mixture of compounds that increase monoaminergic transmission. In particular, we examined whether Ayahuasca changes the activity and connectivity of the DMN and the connection between the DMN and the task-positive network (TPN). Ayahuasca caused a significant decrease in activity through most parts of the DMN, including its most consistent hubs: the Posterior Cingulate Cortex (PCC)/Precuneus and the medial Prefrontal Cortex (mPFC). Functional connectivity within the PCC/Precuneus decreased after Ayahuasca intake. No significant change was observed in the DMN-TPN orthogonality. Altogether, our results support the notion that the altered state of consciousness induced by Ayahuasca, like those induced by psilocybin (another serotonergic psychedelic), meditation and sleep, is linked to the modulation of the activity and the connectivity of the DMN.

Palhano-Fontes, F., Andrade, K. C., Tofoli, L. F., Santos, A. C., Crippa, J., Hallak, J. A., … Araujo, D. B. (2015). The Psychedelic State Induced by Ayahuasca Modulates the Activity and Connectivity of the Default Mode Network. PLoS One. https://dx.doi.org/10.1371/journal.pone.0118143
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Salvinorin A and Related Compounds as Therapeutic Drugs for Psychostimulant-Related Disorders

January 28, 2015 / Addiction, Papers, Psychiatry, Psychology, Psychopharmacology, Publications, Safety, Salvia / Salvinorin A / By / , , ,

Abstract

Pharmacological treatments are available for alcohol, nicotine, and opioid dependence, and several drugs for cannabis-related disorders are currently under investigation. On the other hand, psychostimulant abuse and dependence lacks pharmacological treatment. Mesolimbic dopaminergic neurons mediate the motivation to use drugs and drug-induced euphoria, and psychostimulants (cocaine, amphetamine, and methamphetamine) produce their effects in these neurons, which may be modulated by the opioid system. Salvinorin A is a κ-opioid receptor agonist extracted from Salvia divinorum, a hallucinogenic plant used in magico-ritual contexts by Mazateca Indians in México. Salvinorin A and its analogues have demonstrated anti-addiction effects in animal models using psychostimulants by attenuating dopamine release, sensitization, and other neurochemical and behavioral alterations associated with acute and prolonged administration of these drugs. The objective of the present article is to present an overview of the preclinical evidence suggesting anti-addictive effects of salvinorin A and its analogues.

dos Santos, R. G., Crippa, J. A., Machado-de-Sousa, J. P., & Hallak, J. E. (2015). Salvinorin A and Related Compounds as Therapeutic Drugs for Psychostimulant-Related Disorders. Current Drug Abuse Reviews, 7(2), 128-132. https://dx.doi.org/10.2174/1874473708666150107122741

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