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Mark A. Geyer

54 papers in the library · 2,319 citations · publishing 1975-2026

Papers

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A characteristic effect of hallucinogens on investigatory responding in rats.

Psychopharmacology September 1979 Mark A. Geyer, Roger K. Light, Gary J. Rose et al.

The disruption of the temporal distribution of investigatory responses by rats in a novel hole-board following lysergic acid diethylamide-25 (LSD), as described in a companion paper (Geyer and Light, 1979), was found to be a characteristic effect of a variety of hallucinogens. Similar effects were produced by indoleamine hallucinogens, such as LSD, N,N-dimethyltryptamine, and psilocin, and by...

Mescaline increases startle responding equally in normal and raphe-lesioned rats

Pharmacology, Biochemistry, and Behavior February 1, 1979 Mark A. Geyer, Gary J. Rose, Lyle R. Petersen 7 citations

To test the possible involvement of serotonin-containing cells of the midbrain in mediating the effects of mescaline on startle responding, electrolytic lesions were made in either the dorsal or median raphe nucleus in rats. Decreases in either striatal or hippocampal tryptophan hydroxylase activity confirmed the effectiveness of the lesions. One week later, startle was measured in response to...

The effects of lysergic acid diethylamide and mescaline-derived hallucinogens on sensory-integrative function: tactile startle.

Journal of Pharmacology and Experimental Therapeutics December 1, 1978 Mark A. Geyer, Lyle R. Petersen, Gary J. Rose et al. 69 citations

Tactile startle responding by male Sprague-Dawley rats given 60 presentations of air-puff stimuli (37.5 psi) was measured after the intraperitoneal administration of graded doses of hallucinogens and other psychoactive drugs. Among the drugs tested were the indoleamine-derived compounds, lysergic acid diethylamide (LSD), N,N-dimethyltryptamine and psilocin, and the phenylethylamine-derived...

Opposite effects of intraventricular serotonin and bufotenin on rat startle responses.

Pharmacology, Biochemistry, and Behavior 1975 Mark A. Geyer, J D Warbritton, D B Menkes et al. 34 citations

Rat startle responses to air puffs were monitored in a stabilimeter during the intraventricular infusion of various doses of 5-hydroxytrptamine (5-HT) or the putative hallucinogenic congener of 5-HT, 5-hydroxy-N, N-dimethyltrytamine (5-HDMT) or saline. Qualitativity opposite effects were observed, with 5-HT producing a dose-dependent decrease in responsivity and 5-HDMT increasing the magnitude...