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.

Automated summary

Obsessive-compulsive disorder (OCD) and pathological gambling (PG) are associated with deficits in behavioural flexibility. Model-based functional magnetic resonance imaging (fMRI) reveals altered reward-learning in OCD and PG, with OCD patients showing lower learning rates for worse-than-expected outcomes and attenuated encoding of negative reward prediction errors, and PG patients showing higher and lower learning rates for better- and worse-than-expected outcomes, respectively, accompanied with higher encoding of positive reward prediction errors. Perseveration did not significantly differ between the patient groups and healthy controls.