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| Quantitative Analysis of the Effects of Drugs on Behavior |
| Monday, May 31, 2010 |
| 9:00 AM–10:20 AM |
| Travis C/D (Grand Hyatt) |
| Area: BPH/EAB; Domain: Experimental Analysis |
| Chair: Alice A. Keyl (Utah State University) |
| Abstract: In this symposium, data will be presented on the quantitative analysis of the effects of drugs on behavior. The first presentation, by Keyl and colleagues, focuses on the effects of methylphenidate on the within-session response rates of rats responding on random-interval schedule of food delivery. The second presentation, by Johnson and colleagues, uses the generalized matching law to describe the effects of pre-session pramipexole on rats’ allocation of responding and time spent responding in a concurrent-chains schedule. The third presentation, by Reilly and Hand, examines the responding of rats for sucrose and ethanol solutions, and models the effects of various manipulations with Mathematical Principles of Reinforcement. The fourth presentation, by Pitts and colleagues, describes the effects of morphine on choice in a dynamic environment in which different reinforcer ratios occurred within the same session. Overall, these papers show the utility of characterizing drug effects on behavior using methods of quantitative analysis. |
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| Methylphenidate Changes the Within-Session Pattern of Response Rates of Rats |
| ALICE A. KEYL (Utah State University), Robert N. Johnson (Utah State University), Wesley P. Thomas (Utah State University), Amy Odum (Utah State University) |
| Abstract: Changes in responding during experimental sessions may reflect systematic decreases in reinforcer effectiveness. One important area of interest to examine is the effect of drugs on within-session rates of responding and whether particular drugs potentially enhance or decrease the effectiveness of reinforcers. The present study examined the effects of methylphenidate on the within-session response patterns of 4 rats. Subjects were administered 4 different doses of methylphenidate (3.0 - 17.0 mg/kg) while responding for food pellets on a random-interval 45 s schedule of reinforcement. Under control conditions, on average response rates showed a slight increase, then decrease as the session progressed. Overall, results suggest that methylphenidate increases within-session response rates depending on the dose, indicating slower habituation to the reinforcer. This may have important clinical implications for individuals taking stimulant drugs such as methylphenidate. Specifically, applied researchers may develop ways to maximize these effects on adaptive behaviors (slower habituation to reinforcers). |
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| Effects of Acute Pramipexole on Delay Sensitivity in a Concurrent-Chains Procedure |
| PATRICK S. JOHNSON (University of Kansas), Jeff S. Stein (University of Kansas), Adam T. Brewer (University of Kansas), Monica T. Francisco (University of Kansas), Gregory J. Madden (University of Kansas) |
| Abstract: In recent years, a number of clinical reports have implicated pramipexole, a common component of dopamine replacement therapy for Parkinson’s disease (PD), in the development of impulse control disorders in patients with PD. Experimental evaluations of pramipexole’s effects on traditional measures of impulsivity in humans (Hamidovic, Kang, & de Wit, 2008) and nonhumans (Madden et al., in preparation) have produced mixed results. However, even in the case of positive findings like those of Madden et al.’s Experiment 1, in which acute pramipexole increased rats’ impulsive choices, the specific behavioral mechanism (e.g., delay sensitivity) by which pramipexole modulates choice remains unknown.
The present study used the generalized matching law to describe the effects of pre-session pramipexole on rats’ allocation of responding and time spent responding in a concurrent-chains schedule. Of particular interest were changes in the slopes of linear regressions obtained from drug sessions relative to those from non-drug or saline sessions (i.e., changes in delay sensitivity). Preliminary group findings suggest pramipexole dose-dependently decreased sensitivity to differences in reward delay, as indicated by shallower slopes at larger doses. Given similar decreases in total response output and local response rates, these results are likely attributable to pramipexole’s motor suppressing effects. |
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| Quantifying Oral Ethanol Reinforcement Using Mathematical Principles of Reinforcement |
| MARK P. REILLY (Central Michigan University), Dennis J. Hand (Central Michigan University) |
| Abstract: Two experiments will be presented that involve rats lever pressing under fixed-ratio schedules for access to a liquid solution. The solution consisted of various concentrations of sucrose and ethanol, depending on the experiment and condition. The response rates were modeled using mathematical principles of reinforcement, with an emphasis on the effects the various solutions have on the free parameter, a, representing specific activation. This parameter is interpreted to reflect reinforcer effectiveness. One experiment involved a commonly-used fading technique in which the sucrose concentration is decreased from an ethanol solution across conditions. Another experiment involved a comparison of ethanol reinforcement in two groups of rats, where one group received experiences with drinking ethanol beforehand and outside the operant chamber. Overall, ethanol’s reinforcing effectiveness was modest and greatly reduced at lower sucrose concentrations. Prior experience with ethanol resulted in better maintenance of response rates but only at lower ratio values, a finding which possibly constrains the application MPR. The results stress the importance of considering pharmacological and taste-related components of oral ethanol reinforcement. |
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| Effects of Morphine on Choice in a Dynamic Environment |
| RAYMOND C. PITTS (University of North Carolina, Wilmington), David A Pelley (University of North Carolina, Wilmington), Christine E. Hughes (University of North Carolina, Wilmington) |
| Abstract: Four pigeons responded under concurrent schedules of food presentation in which seven components were arranged within a mixed schedule (i.e., components were unsignaled). Each component programmed a different left:right reinforcer ratio (1:27, 1:9, 1:3, 1:1, 3:1, 9:1, 27:1). Components occurred in a random order within each session, ended after 10 reinforcer presentations, and were separated by 10-s blackouts. After sufficient exposure to these dynamic conditions: a) preference adjusted rapidly (i.e., sensitivity to reinforcement increased) within components; b) preference for a given alternative increased with successive reinforcer deliveries via that alternative (“confirmations”), but was substantially attenuated following a reinforcer delivery via the other alternative (a “disconfirmation”); and c) food deliveries produced immediate, local, increases in preference for the just-reinforced alternative (“preference pulses”). Effects of various doses of morphine on the dynamic structure of choice were determined. These effects may have resulted from a disruption of stimulus control by individual reinforcer presentations. |
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