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Behavioral momentum of cocaine self-administration: effects of frequency of reinforcement on resistance to extinction

Quick, Stacey L.; Shahan, Timothy A.

doi: 10.1097/FBP.0b013e32832f01a8
Original Articles

Persistent drug seeking is a defining property of substance abuse and is generally thought to depend, in part, on exposure to drug-associated contexts. Behavioral momentum theory provides a set of methods and a theoretical framework for understanding how stimulus contexts contribute to the persistence of operant behavior. Earlier research has extended behavioral momentum theory to alcohol self-administration, but not to intravenous drug self-administration. This experiment extended behavioral momentum theory to cocaine self-administration by examining the effects of frequency of cocaine reinforcement in a context on resistance to extinction. Rats self-administered 0.32 mg/kg infusions of cocaine in a multiple schedule of reinforcement arranging two distinct contexts. Responding in a Rich context was reinforced by cocaine infusions at a higher frequency (i.e. variable interval 120 s) and in a Lean context at a lower frequency (variable interval 360 s). After establishment of responding in the two contexts, resistance to extinction was examined. Preextinction response rates for cocaine were similar in the Rich and Lean contexts. Nonetheless, relative resistance to extinction was greater in the Rich context than in the Lean context. The difference in resistance to extinction in the two contexts was well described by a quantitative model of behavioral momentum. These results suggest that the frequency of drug reinforcement in a context contributes to the persistence of drug seeking in that context, and that behavioral momentum theory might be useful for understanding how drug-associated contexts contribute to the persistence of drug seeking.

Department of Psychology, Utah State University, Logan, Utah, USA

Correspondence to Dr Timothy A. Shahan, PhD, Department of Psychology, 2810 Old Main Hill, Utah State University, Logan, UT 84322, USA

E-mail: tim.shahan@usu.edu

Received 26 February 2009 Accepted as revised 1 June 2009

© 2009 Lippincott Williams & Wilkins, Inc.