@article{df283293c95147e9a7d5f83c76d97074,
title = "Variable interval responding maintained by intravenous codeine and ethanol injections in the rhesus monkey",
abstract = "Rhesus monkeys were trained to respond under a variable interval 2 min schedule for codeine or ethanol injections. Both codeine and ethanol were effective in the initiation of variable-interval responding; responding was maintained over a range of codeine (0.003-1.0 mg/kg/injection) and ethanol doses (32.0-560 mg/kg/injection). Maximum rates of responding were obtained at the 0.01 mg/kg/injection codeine dose (0.14 responses/sec) and at the 180 mg/kg/injection codeine dose (0.19 responses/sec). Rates of responsing were bitonic functions of the reinforcer dose for both codeine and ethanol; maximum rates were obtained at intermediate doses and lower rates occurred at the extremes of the dose range. Both codeine and ethanol showed within-session decreases in responding across the range of reinforcer doses. Codeine-reinforced responding declined in rate within the one-hour session without a similar change in the frequency of drug injection; in contrast, both ethanol-reinforced responding and the frequency of ethanol injections declined within each session across a range of doses. Increasing or decreasing the codeine dose half-way through the one-hour session resulted in increases or decreases in codeine responding compared to controls. These data indicate that the progressive decline in codeine-reinforced responding is not the result of a generalized disruption of responding.",
keywords = "Codeine, Ethanol, Schedule of reinforcement, Self-administration, Variable interval",
author = "Carney, {John M.} and Llewellyn, {Mark E.} and Woods, {James H.}",
note = "Funding Information: In the majority of the self-administration studies in which negative acceleration was observed, drug reinforcement was available under FR schedules. A feature of FR schedules is that the rate of responding determines the frequency of reinforcer delivery. Thus, a negatively accelerated pattern of FR responding would result in a negatively accelerated pattern of drug injections. In contrast to FR schedules, under a variable interval (VI) schedule of reinforcement, responses are reinforced on the basis of the time since the last reinforcement \[3\]. For this reason, the frequency of reinforcer delivery under a VI schedule is relatively independent of the rate of responding across a wide range of response rates. The first purpose of the present study, therefore, was to determine if the dose-related negative acceleration of responding observed for ethanol and codeine reinforcement under FR schedules would also occur under a VI schedule of reinforcement. The second purpose was to quantitatively describe the relationship between the reinforcer dose of codeine or ethanol and the degree of negative acceleration observed. The third purpose was to determine the effects of changing ' This research was supported in part by USPHS Grant DA00154 and GM00198. 2 Predoctoral trainee in Pharmacology supported by USPHS Grant GM00198. Present address: Department of Pharmacology, MCV Station 726, Medical College of Virginia, Richmond, VA 23298. 3 Predoctoral trainee in Psychology supported by an Addiction Research Foundation of Ontario Fellowship. 4 Send reprint requests to: Dr. James H. Woods, Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48104.",
year = "1976",
month = nov,
doi = "10.1016/0091-3057(76)90272-0",
language = "English (US)",
volume = "5",
pages = "577--582",
journal = "Pharmacology Biochemistry and Behavior",
issn = "0091-3057",
publisher = "Elsevier Inc.",
number = "5",
}