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EFFECTS OF METHYLPHENIDATE AND MORPHINE ON DELAY-DISCOUNT FUNCTIONS OBTAINED WITHIN SESSIONS.
- Source :
-
Journal of the Experimental Analysis of Behavior . May2005, Vol. 83 Issue 3, p297-314. 18p. - Publication Year :
- 2005
-
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 tingle 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. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00225002
- Volume :
- 83
- Issue :
- 3
- Database :
- Academic Search Index
- Journal :
- Journal of the Experimental Analysis of Behavior
- Publication Type :
- Academic Journal
- Accession number :
- 17400475
- Full Text :
- https://doi.org/10.1901/jeab.2005.47-04