Alcohol effects on human aggressive behavior: influence of concurrent fixed-ratio reinforcement contingencies.
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Biomedical subjects
Publications and source records attributed to T H Kelly.
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Male research subjects were administered placebo and three doses of d-amphetamine (5, 10 and 20 mg/70 kg) in a laboratory situation which provided both aggressive and non-aggressive response options. The non-aggressive response was button pressing maintained by presentation of points exchangeable for money at the end of the session. The aggressive response was button pressing on a separate manipulanda which ostensibly subtracted points from a fictitious partner. Aggressive responding was elicited by subtracting points from the research subjects which was attributed to the fictitious partner. d-Amphetamine increased both aggressive and non-aggressive responding, particularly at 5 and 10 mg/70 kg. At the highest dose (20 mg/70 kg), aggressive responding decreased to levels similar to those observed during placebo sessions, while monetary reinforced responding remained elevated.
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Effects of methadone on key pecking supplemented with brief stimuli either correlated with or independent of unconditioned reinforcement was investigated. On average, key pecks by pigeons produced brief stimuli (BS) once per minute and food once per 4 min during both components of a multiple schedule (i.e., VI1 : BS, VI4 : Food). Brief stimuli were paired with food presentation during one component and not related to food during the second component. Acute methadone administration (0.56, 1.0, 1.7, and 3.0 mg/kg) decreased response rates during both components; however, the decrease was smaller by a constant amount during the paired brief stimulus component, regardless of drug dose. These results suggest conditioned reinforcement is not a primary mechanism through which methadone exerts behavioral effects and that reinforcer-correlated stimuli have potential for diminishing the reduced behavioral output observed following methadone administration.
Five adult male White Carneaux pigeons, maintained at approximately 70, 80 or 90% free-feeding weight, were administered methadone (0.5, 1.5, and 2.5 mg/kg) prior to sessions of key pecking maintained under 5-min fixed-interval schedules of food presentation. Increasing deprivation levels attenuated the rate-decreasing effects of methadone. Methadone effects on pause time were unchanged. Three pigeons, maintained at 80% free-feeding weight were then administered methadone hydrochloride (0.62, 1.25 and 2.5 mg/kg) and naloxone hydrochloride (.0001, .0003, .001, .003 or .01 mg/kg) alone and in combination while responding under these same contingencies. Naloxone had no systematic behavioral effects alone but antagonized methadone's effects on fixed-interval responding and pausing. Naloxone also altered methadone's rate-dependent effects. These results suggest the behavioral effects of methadone are differentially altered following food-deprivation and opiate antagonist manipulations.