Neural basis of anhedonia as a failure to predict pleasantness in schizophrenia

Objectives. Anhedonia in schizophrenia results from a deficit in anticipatory pleasure rather than consummatory pleasure. This study aimed to determine the neural basis of the predictive and experiential components of anticipatory pleasure in schizophrenia. Methods. A hedonic rating task was performed by 15 patients with schizophrenia and 17 controls while undergoing functional magnetic resonance imaging. Participants evaluated the level of pleasantness for the preview/predictive phase, comprising a narration and adjunctive audiovisual stimuli for pleasurable experience, and the subsequent viewing/experiential phase, comprising a video clip for a pleasant event. Results. A significant group-by-phase interaction was seen in the rostral anterior cingulate cortex (ACC) and caudate, resulting from reduced activations in patients during the preview phase. Patients showed significantly reduced activation in the frontopolar cortex and rostral ACC during the preview phase. The signal changes in the caudate and frontopolar cortex were associated with increase in hedonic response during the sequential pleasure experiences. Conclusions. Augmentation of hedonic enjoyment between the predictive and experiential stages of anticipatory pleasure is reduced in schizophrenia because of diminished activity in the reward-related regions during the prediction of pleasure. During cued-emotional experiences of anticipatory pleasure, patients seem to have difficulties in the integration of emotional information.