Date of Award:

2016

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Psychology

Advisor/Chair:

Gregory J. Madden

Abstract

Impulsive choice (i.e., preference for smaller, sooner over larger, later rewards) is cross-sectionally and longitudinally associated with drug dependence in humans. Similarly, impulsive choice is associated with greater drug self-administration in rodents. These findings suggest that impulsive choice plays a causal role in drug use. However, little research has been designed to experimentally test this hypothesis or the boundary conditions under which it may operate.

The research reported in this document examined the relation between impulsive choice and alcohol consumption in rats. We developed and refined an experimental method, in which rats were pre-exposed to delayed rewards, to produce trait-like reductions in impulsive choice. We then examined the effects of this manipulation on subsequent alcohol consumption. If impulsive choice is causally related to alcohol consumption in this rodent model, then reduction of impulsive choice should be accompanied by a reduction in alcohol consumption. However, in the experiment presented in Chapter 2, reductions in impulsive choice for food rewards were accompanied by unexpected increases in alcohol consumption. Accordingly, the goals of the experiments in Chapters 3 and 4 were to help determine the conditions that produced this unexpected finding.

Results reported in Chapters 3 and 4 suggest that the unexpected results reported in Chapter 2 were dependent on the way in which alcohol was introduced in that experiment and perhaps other variables specific to orally consumed alcohol (e.g., taste, slow onset of pharmacological effects). Moreover, in Chapter 3, examination of our own and newly reported data suggests that the naturally occurring relation between impulsive choice and alcohol consumption in rodents is not as robust as it is for other drugs of abuse (e.g., psychostimulants, such as cocaine or nicotine). Nonetheless, the work reported in these experiments developed a method of reducing impulsive choice which may be used in future research to examine its related effects on consumption of other drugs of abuse.

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