Effects of Methylphenidate and Morphine on Delay-Discount Functions Obtained within Sessions

Autor/inn/en	Pitts, Raymond C.; McKinney, A. Patrick
Titel	Effects of Methylphenidate and Morphine on Delay-Discount Functions Obtained within Sessions
Quelle	In: Journal of the Experimental Analysis of Behavior, 83 (2005) 3, S.297-314 (18 Seiten) PDF als Volltext Verfügbarkeit
Sprache	englisch
Dokumenttyp	gedruckt; online; Zeitschriftenaufsatz
ISSN	0022-5002
Schlagwörter	Reinforcement; Drug Use; Animals; Animal Behavior; Behavioral Science Research; Delay of Gratification + Suchen Sie Ihr Suchwort? Positive Verstärkung; Drug consumption; Substance abuse; Drogenkonsum; Animal; Tier; Tiere; Tierverhalten
Abstract	Four rats responded under a "self-control" procedure designed to obtain delay- discount functions within sessions. Each session consisted of seven blocks, with seven trials within each block. Each block consisted of two initial forced- choice trials followed by five free-choice trials. On choice trials, the rats could press either of two retractable levers. A press on one lever was followed by presentation of a smaller reinforcer (a single dipper presentation of a sucrose solution); a press on the other lever was followed by presentation of a larger reinforcer (four consecutive dipper presentations). The delay associated with the smaller reinforcer always was 0 s, whereas the signaled delay associated with the larger reinforcer increased across blocks (from 0 to 50 s). Under these conditions, the percentage of choices of the larger reinforcer decreased across blocks, and relatively reliable delay-discount functions were obtained within sessions. Doses of methylphenidate (1.0 to 17.0 mg/kg) and morphine (0.3 to 17.0 mg/kg) were then administered prior to selected sessions. Typically, intermediate doses of methylphenidate shifted the discount functions to the right (increased choices of the larger reinforcer). For 2 of the rats, this effect was pronounced; for the other 2 rats, this effect occurred after the range of delays for the larger reinforcer was decreased (0 to 20 s). On the other hand, in most cases morphine produced a slight leftward shift in the discount function (decreased choices of the larger reinforcer). The present procedure appears to be a useful and efficient method to characterize drug effects on an entire delay-discount function. As with many procedures used to study self-control choices, however, sources of control other than reinforcement delay and amount may have been operating in the present study, and these sources must be considered when interpreting drug effects. (Contains 2 tables and 6 figures.) (As Provided).
Anmerkungen	Society for the Experimental Analysis of Behavior. Available from: Indiana University Department of Psychology. Bloomington, IN 47405. Tel: 812-334-0395; Fax: 812-855-4691; e-mail: jeab@indiana.edu; Web site: http://seab.envmed.rochester.edu/jeab/index.html
Erfasst von	ERIC (Education Resources Information Center), Washington, DC
Update	2017/4/10