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Objective: Negative symptoms can be grouped into two factors, expressive deficits and social-emotional withdrawal. We aimed to examine the neural correlates of the two negative symptom factors during a social cognition task, which measures emotional ambiguity in a social context by presenting an array of faces with varying degrees of consistency in emotional expressions. Methods: Patients with schizophrenia (N=38) and healthy controls (N=20) performed a social cognition task during fMRI that probed both affect and ambiguity. Differences in brain activation between the healthy controls and patients were non-parametrically tested. Subsequently, the expressive deficits and social-emotional withdrawal factors were regressed against task-related brain activation. Results: Severity of expressive deficits was negatively correlated with activation of the ventromedial prefrontal cortex when comparing ambiguous emotional decisions to ambiguous gender decisions. During emotional ambiguity, severity of expressive deficits was negatively correlated with activation in thalamic, prefrontal, precentral, parietal and temporal brain areas. No associations between social-emotional withdrawal and brain activation were observed. Conclusion: Hypoactivation of the fronto-thalamic circuitry during ambiguous social appraisal may imply a reduced action readiness in social situations, underlying expressive deficits but not social-emotional withdrawal. The findings provide further evidence for different neurobiological bases of the two factors of negative symptoms.