STEADY-STATE ASSESSMENT OF IMPULSIVE CHOICE IN LEWIS AND FISCHER 344 RATS: BETWEEN-CONDITION DELAY MANIPULATIONS

• Published in: Journal of the experimental analysis of behavior Vol. 90; no. 3; pp. 333 - 344
• Main Authors: Madden, Gregory J., Smith, Nathaniel G., Brewer, Adam T., Pinkston, Jonathan W., Johnson, Patrick S.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.11.2008; Society for the Experimental Analysis of Behavior; Society for the Experimental Analysis of Behavior, Inc
• Subjects: Animal Behavior; Animals; Behavior, Animal - physiology; Behavioral Science Research; choice; Choice Behavior; Conceptual Tempo; Decision Making; Delay of Gratification; delay-discounting; Drug Use; Evidence; Fischer 344 rats; Food; Genetics; Impulsive Behavior; impulsivity; Individual Characteristics; lever press; Lewis rats; Neurological Organization; Preferences; rat; Rats; Rats, Inbred F344; Rats, Inbred Lew; Reinforcement; Reinforcement (Psychology); Self Control; Standard deviation; Studies
• ISSN: 0022-5002; 1938-3711; 0022-5002
• DOI: 10.1901/jeab.2008.90-333

Previous research has shown that Lewis rats make more impulsive choices than Fischer 344 rats. Such strain‐related differences in choice are important as they may provide an avenue for exploring genetic and neurochemical contributions to impulsive choice. The present systematic replication was designed to determine if these findings could be reproduced using a procedure less susceptible to within‐ or between‐session carry‐over effects that may have affected previous findings. Specifically, delays to the larger‐later food reinforcer were manipulated between conditions following steady‐state assessments of choice, and the order of delays across conditions was mixed. The results confirmed previous findings that Lewis rats made significantly more impulsive choices than Fischer 344 rats. Fischer 344 rats' preference for the larger‐later reinforcer, on the other hand, was less extreme than reported in prior research, which may be due to carry‐over effects inherent to the commonly used technique of systematically increasing delays within session. Previously reported across‐strain motor differences were reproduced as Lewis rats had shorter latencies than Fischer 344 rats, although these latencies were not correlated with impulsive choice. Parallels between reduced dopamine function in Lewis rats and clinical reports of impulse‐control disorders following treatment of Parkinson patients with selective D2/D3 dopamine agonists are discussed.