Altered activation in association with reward-related trial-and-error learning in patients with schizophrenia

In patients with schizophrenia, the ability to learn from reinforcement is known to be impaired. The present fMRI study aimed at investigating the neural correlates of reinforcement-related trial-and-error learning in 19 schizophrenia patients and 20 healthy volunteers. A modified gambling paradigm was applied where each cue indicated a subsequent number which had to be guessed. In order to vary predictability, the cue-number associations were based on different probabilities (50%, 81%, 100%) which the participants were not informed about. Patients' ability to learn contingencies on the basis of feedback and reward was significantly impaired. While in healthy volunteers increasing predictability was associated with decreasing activation in a fronto-parietal network, this decrease was not detectable in patients. Analysis of expectancy-related reinforcement processing yielded a hypoactivation in putamen, dorsal cingulate and superior frontal cortex in patients relative to controls. Present results indicate that both reinforcement-associated processing and reinforcement learning might be impaired in the context of the disorder. They moreover suggest that the activation deficits which patients exhibit in association with the processing of reinforcement might constitute the basis for the learning deficits and their accompanying activation alterations.