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Observational Determination of Dose-Response Curves in Hallucinogen-Treated Monkeys

J.M. Brewster, Ronald K. Siegel, C.A. Johnson, Murray E. Jarvik

International Pharmacopsychiatry August 11, 2017 DOI: 10.1159/000468218 (opens in new tab)

Study at a glance

AI-extracted from the abstract
Characteristics Experimental study Peer reviewed
Population Adolescent rhesus monkeys
Intervention Dimethyltryptamine (DMT)
Dose five doses
Key findings DMT produced dose-dependent increases in several behaviors, and certain hallucinogen-sensitive behaviors emerged more frequently in darkness without external stimuli.

Abstract

An objective behavioral profile that was previously shown to distinguish the effects of hallucinogens from those of other classes of drugs was used here to further study hallucinogenic behaviors. Saline, d-amphetamine sulfate and five doses of dimethyltryptamine (DMT) were administered to solitary adolescent rhesus monkeys in a totally dark environment and their behavior was observed via infrared monitors, videotaped, and scored in a number of categories. Scores in the following categories systematically increased with ascending doses of DMT: exploration, locomotion, stereotypy, spasm, tracking and duration of inappropriate behavior. In addition, some behaviors sensitive to hallucinogens occurred with greater frequency in the dark than in a previous study conducted in the light. Behaviors such as tracking and fear grimaces, usually associated with specific stimuli, emerged in the absence of such stimuli in the dark. These results suggested hallucinogen-induced changes in perceptual-motor systems, if not hallucinations per se.