This re-analysis of a double-blind, placebo-controlled clinical study (n=18) investigated whether ayahuasca (42 & 59.5mg/70kg DMT) impairs the ability to filter out unnecessary sensory information in healthy volunteers. This yielded mixed results, with evidence to support that ayahuasca impairs sensorimotor gating in the domain of auditory suppression, but not within the domain of visual-induced prepulse inhibition of the startle reflex.
Abstract of Effects of ayahuasca on sensory and sensorimotor gating in humans
“Rationale: Ayahuasca, a South American psychotropic plant tea, combines the psychedelic agent and 5-HT(2A/2C) agonist N, N-dimethyltryptamine (DMT) with beta-carboline alkaloids showing monoamine oxidase-inhibiting properties. Current human research with psychedelics and entactogens has explored the possibility that drugs displaying agonist activity at the 5-HT(2A/2C) sites temporally disrupt inhibitory neural mechanisms thought to intervene in the normal filtering of information. Suppression of the P50 auditory evoked potential (AEP) and prepulse inhibition of startle (PPI) are considered operational measures of sensory (P50 suppression) and sensorimotor (PPI) gating. Contrary to findings in lower animals, unexpected increases in sensorimotor gating have been found in humans following the administration of the serotonergic psychedelic psilocybin and the serotonin releaser 3,4-methylenedioxymethamphetamine (MDMA). In addition, to our knowledge P50 suppression has not been assessed previously in humans following the administration of a 5-HT(2A/2C) agonist.
Objectives: To assess the effects of the acute administration of ayahuasca on P50 suppression and PPI in humans, in order to evaluate the drug’s modulatory actions on these measures of sensory and sensorimotor gating.
Methods: Eighteen healthy volunteers with prior experience of psychedelic drug use participated in a clinical trial in which placebo or ayahuasca doses (0.6 mg and 0.85 mg DMT/kg body weight) were administered according to a double-blind, cross-over balanced design. P50 and startle reflex (pulse-alone and 60 ms, 120 ms, 240 ms and 2000 ms prepulse-to-pulse intervals) recordings were undertaken at 1.5 h and 2 h after drug intake, respectively.
Results: Ayahuasca produced diverging effects on each of the two gating measures evaluated. Whereas significant dose-dependent reductions of P50 suppression were observed after ayahuasca, no significant effects were found on the startle response, its habituation rate, or on PPI at any of the prepulse-to-pulse intervals studied.
Conclusion: The present findings indicate, at the doses tested, a decremental effect of ayahuasca on sensory gating, as measured by P50 suppression, and no distinct effects on sensorimotor gating, as measured by PPI.”
Authors: Jordi Riba, Antoni Rodríguez-Fornells & Manel J. Barbanoj
Summary of Effects of ayahuasca on sensory and sensorimotor gating in humans
Eighteen healthy volunteers were included in the study. They had prior experience with psychedelic drugs, cannabis, and cocaine, and were given a structured psychiatric interview and completed the trait-anxiety scale from the State-Trait Anxiety Inventory. The study was conducted following the Declarations of Helsinki and Tokyo concerning experimentation on humans, and all volunteers gave their written informed consent to participate.
Two doses of ayahuasca containing 0.6 mg and 0.85 mg DMT/kg body weight were chosen as the low and high doses based on tolerability and subjective effects assessed in a previous study. The ayahuasca was administered as a freeze-dried homogenized material obtained from a 9.6-l batch of Daime obtained from Cefluris.
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https://doi.org/10.1007/s00213-002-1237-5
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Cite this paper (APA)
Riba, J., Rodríguez-Fornells, A., & Barbanoj, M. J. (2002). Effects of ayahuasca on sensory and sensorimotor gating in humans as measured by P50 suppression and prepulse inhibition of the startle reflex, respectively. Psychopharmacology, 165, 18-28.
Study details
Compounds studied
Ayahuasca
Topics studied
Neuroscience
Study characteristics
Original Re-analysis
Placebo-Controlled
Double-Blind
Within-Subject
Randomized
Participants
18
Humans
Authors
Authors associated with this publication with profiles on Blossom
Jordi RibaJordi Riba (1968 - 2020†) was a pioneering ayahuasca researcher who dedicated over two decades of work to the field. His work focussed on the pharmacokinetics and pharmacodynamics of ayahuasca, including alkaloid disposition, and electroencephalography, and neuroimaging measures of acute ayahuasca effects. He also conducted several studies on centrally-acting drugs on the acute and long-term effects of psychedelics, psychostimulants, cannabinoids, sedatives, and kappa-opioid receptor agonists. His later work moved towards investigating the neural and psychological mechanisms that could underlie the beneficial effects of ayahuasca in the treatment of various psychiatric conditions.
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Institutes associated with this publication
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Compound Details
The psychedelics given at which dose and how many times
Ayahuasca 42 - 60mg | 2x
Linked Research Papers
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Topographic pharmaco-EEG mapping of the effects of the South American psychoactive beverage ayahuasca in healthy volunteersThis double-blind, crossover, placebo-controlled clinical study (n=18) investigated the effects of ayahuasca (42-60mg DMT/70kg) on temporal brain activity in healthy volunteers and found an absolute power decrease in all frequency bands measured with EEG, which paralleled the time course of its subjective effects.