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Impairments in reinforcement learning do not explain enhanced habit formation in cocaine use disorder

Published version
Peer-reviewed

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Authors

Lim, T. V. 
Cardinal, R. N. 
Savulich, G. 
Jones, P. S. 
Moustafa, A. A. 

Abstract

Abstract: Rationale: Drug addiction has been suggested to develop through drug-induced changes in learning and memory processes. Whilst the initiation of drug use is typically goal-directed and hedonically motivated, over time, drug-taking may develop into a stimulus-driven habit, characterised by persistent use of the drug irrespective of the consequences. Converging lines of evidence suggest that stimulant drugs facilitate the transition of goal-directed into habitual drug-taking, but their contribution to goal-directed learning is less clear. Computational modelling may provide an elegant means for elucidating changes during instrumental learning that may explain enhanced habit formation. Objectives: We used formal reinforcement learning algorithms to deconstruct the process of appetitive instrumental learning and to explore potential associations between goal-directed and habitual actions in patients with cocaine use disorder (CUD). Methods: We re-analysed appetitive instrumental learning data in 55 healthy control volunteers and 70 CUD patients by applying a reinforcement learning model within a hierarchical Bayesian framework. We used a regression model to determine the influence of learning parameters and variations in brain structure on subsequent habit formation. Results: Poor instrumental learning performance in CUD patients was largely determined by difficulties with learning from feedback, as reflected by a significantly reduced learning rate. Subsequent formation of habitual response patterns was partly explained by group status and individual variation in reinforcement sensitivity. White matter integrity within goal-directed networks was only associated with performance parameters in controls but not in CUD patients. Conclusions: Our data indicate that impairments in reinforcement learning are insufficient to account for enhanced habitual responding in CUD.

Description

Keywords

Original Investigation, Goal-directed learning/behaviour, Habit, Computational modelling, Hierarchical Bayesian, Appetitive discrimination learning, Reinforcement sensitivity, Positive feedback, Extinction, Perseveration

Journal Title

Psychopharmacology

Conference Name

Journal ISSN

0033-3158
1432-2072

Volume Title

236

Publisher

Springer Berlin Heidelberg