Individuals with problem gambling and obsessive-compulsive disorder learn through distinct reinforcement mechanisms.

Obsessive-compulsive disorder (OCD) and pathological gambling (PG) are accompanied by deficits in behavioural flexibility. In reinforcement learning, this inflexibility can reflect asymmetric learning from outcomes above and below expectations. In alternative frameworks, it reflects perseveration independent of learning. Here, we examine evidence for asymmetric reward-learning in OCD and PG by leveraging model-based functional magnetic resonance imaging (fMRI). Compared with healthy controls (HC), OCD patients exhibited a lower learning rate for worse-than-expected outcomes, which was associated with the attenuated encoding of negative reward prediction errors in the dorsomedial prefrontal cortex and the dorsal striatum. PG patients showed higher and lower learning rates for better- and worse-than-expected outcomes, respectively, accompanied by higher encoding of positive reward prediction errors in the anterior insula than HC. Perseveration did not differ considerably between the patient groups and HC. These findings elucidate the neural computations of reward-learning that are altered in OCD and PG, providing a potential account of behavioural inflexibility in those mental disorders.
Competing Interests: I have read the journal’s policy and the authors of this manuscript have the following competing interests: M.Y. receives funding from National Health and Medical Research Council of Australia schemes, Monash University, and Australian Government funding bodies such as the Australian Research Council, Australian Defence Science and Technology, and the Department of Industry, Innovation and Science. He has also received philanthropic donations from the David Winston Turner Endowment Fund, Wilson Foundation, as well as payments in relation to court-, expert witness-, and/or expert review-reports. Finally, he has received funding to conduct sponsored Investigator-Initiated trials (including Incannex Healthcare Ltd). He also sits on the Advisory Boards of Centre of The Urban Mental Health, University of Amsterdam; Enosis Therapeutics; and Monash Biomedical Imaging Centre. L.P. was supported by the National Institute Of Mental Health of the National Institutes of Health (K99MH127296) and a 2020 NARSAD Young Investigator Grant from the Brain & Behavior Research Foundation. The other authors declare no competing interests.
(Copyright: © 2023 Suzuki et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)