Christa A Houck1, Nicholas J Grahame2. 1. Department of Psychology, Indiana University-Purdue University Indianapolis, 402 N. Blackford Street, Indianapolis, IN, 46202, USA. 2. Department of Psychology, Indiana University-Purdue University Indianapolis, 402 N. Blackford Street, Indianapolis, IN, 46202, USA. ngrahame@iupui.edu.
Abstract
RATIONALE: Drug reward plays a central role in acquiring drug-seeking behavior. However, subjects may continue using drugs despite negative consequences because self-administration becomes habitual, and divorced from outcome values. Although a history of drug and alcohol use expedite habit acquisition, and in spite of the fact that self-administration leads to intoxication, the acute effects of drugs on habitual responding are not well understood. OBJECTIVES: We sought to observe how acute ethanol and amphetamine affect the balance between habitual and goal-directed behavior, as measured by a fluid-reinforced operant conditioning task. METHODS: Selectively bred crossed high-alcohol-preferring (cHAP) mice were trained on an operant conditioning task reinforced on a variable interval schedule with 1% banana solution, which was subsequently devalued via LiCl pairing in half the animals. Ethanol (1.0 g/kg), amphetamine (2.0 mg/kg), or saline was administered prior to a post-devaluation test. RESULTS: Overall, mice showed habitual behavior, but when divided into high- or low-responding groups based on training response rates, saline-treated, low-responding animals devalued, while saline-treated high-responding animals did not. Furthermore, amphetamine elicited devaluation even in high-responding animals, while ethanol prevented devaluation even in low-responding animals. CONCLUSIONS: These data show that ethanol shifts animals toward behaving habitually. This may illuminate why alcohol-intoxicated individuals display impaired judgment about the relative merits of drinking, and potentially serve as a mechanism by which intoxicated subjects resume previously devalued behaviors, such as comorbid drug use. These findings also show that high variable interval response rates facilitate a shift from goal-directed to habitual behavior.
RATIONALE: Drug reward plays a central role in acquiring drug-seeking behavior. However, subjects may continue using drugs despite negative consequences because self-administration becomes habitual, and divorced from outcome values. Although a history of drug and alcohol use expedite habit acquisition, and in spite of the fact that self-administration leads to intoxication, the acute effects of drugs on habitual responding are not well understood. OBJECTIVES: We sought to observe how acute ethanol and amphetamine affect the balance between habitual and goal-directed behavior, as measured by a fluid-reinforced operant conditioning task. METHODS: Selectively bred crossed high-alcohol-preferring (cHAP) mice were trained on an operant conditioning task reinforced on a variable interval schedule with 1% banana solution, which was subsequently devalued via LiCl pairing in half the animals. Ethanol (1.0 g/kg), amphetamine (2.0 mg/kg), or saline was administered prior to a post-devaluation test. RESULTS: Overall, mice showed habitual behavior, but when divided into high- or low-responding groups based on training response rates, saline-treated, low-responding animals devalued, while saline-treated high-responding animals did not. Furthermore, amphetamine elicited devaluation even in high-responding animals, while ethanol prevented devaluation even in low-responding animals. CONCLUSIONS: These data show that ethanol shifts animals toward behaving habitually. This may illuminate why alcohol-intoxicated individuals display impaired judgment about the relative merits of drinking, and potentially serve as a mechanism by which intoxicated subjects resume previously devalued behaviors, such as comorbid drug use. These findings also show that high variable interval response rates facilitate a shift from goal-directed to habitual behavior.
Authors: Michael S McCloskey; Mitchell E Berman; David J Echevarria; Emil F Coccaro Journal: Alcohol Clin Exp Res Date: 2009-01-12 Impact factor: 3.455
Authors: Z Sjoerds; S de Wit; W van den Brink; T W Robbins; A T F Beekman; B W J H Penninx; D J Veltman Journal: Transl Psychiatry Date: 2013-12-17 Impact factor: 6.222