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

Area of Science:

• Neuroscience
• Psychiatry
• Computational Psychiatry

Background:

• Obsessive-compulsive disorder (OCD) and pathological gambling (PG) are characterized by behavioral inflexibility.
• This inflexibility may stem from asymmetric reward learning, where individuals learn differently from better-than-expected versus worse-than-expected outcomes.
• Alternative theories suggest perseveration, independent of learning, might explain this inflexibility.

Purpose of the Study:

• To investigate asymmetric reward learning in OCD and PG using model-based functional magnetic resonance imaging (fMRI).
• To identify the neural correlates of altered reward learning in these disorders.
• To differentiate between learning deficits and perseveration as causes of behavioral inflexibility.

Main Methods:

• Employed model-based fMRI to analyze reward learning in patients with OCD, PG, and healthy controls (HC).
• Quantified learning rates for outcomes above and below expectations.
• Examined neural encoding of reward prediction errors in key brain regions.

Main Results:

• OCD patients demonstrated a reduced learning rate for worse-than-expected outcomes, linked to attenuated negative reward prediction error encoding in the dorsomedial prefrontal cortex and dorsal striatum.
• PG patients exhibited higher learning rates for better-than-expected outcomes and lower rates for worse-than-expected outcomes, with enhanced positive reward prediction error encoding in the anterior insula.
• No significant differences in perseveration were observed between patient groups and HC.

Conclusions:

• OCD and PG involve distinct alterations in the neural computation of reward learning.
• Asymmetric reward learning, particularly deficits in learning from negative feedback in OCD and biased learning in PG, provides a potential explanation for behavioral inflexibility in these disorders.
• Findings highlight specific neurobiological mechanisms underlying reward processing deficits in psychiatric conditions.