Computational and neural evidence for altered fast and slow learning from losses in gambling disorder

Learning occurs across multiple timescales, with fast learning crucial for adapting to sudden environmental changes, and slow learning beneficial for extracting robust knowledge from multiple events. Here we asked if miscalibrated fast vs slow learning can lead to maladaptive decision-making in individuals with gambling disorder. Participants with problem gambling and a recreational gambling control group without any symptoms associated with problem gambling performed a probabilistic decision-making task involving reward-learning and loss-avoidance while being scanned with fMRI. Problem gamblers showed impaired reversal learning from losses compared to the control group, with excessive dependence on slow timescales and reduced reliance on fast timescales. fMRI data implicated the putamen, an area associated with habit, and medial prefrontal cortex (PFC) in slow loss-value encoding, with significantly more robust encoding in medial PFC in problem gamblers compared to controls. Problem gamblers also exhibited stronger loss prediction error encoding in the insular cortex. These findings suggest that individuals with problem gambling have an impaired ability to adjust their predictions following losses, manifested by a stronger influence of slow value learning. This impairment could contribute to the behavioral inflexibility of problem gamblers, particularly the persistence in gambling behavior typically observed in those individuals after incurring loss outcomes.