Orbito-frontal lesions cause impairment during late but not early emotional prosodic processing

The orbitofrontal cortex (OFC) is functionally linked to a variety of cognitive and emotional functions. In particular, lesions of the human OFC lead to large-scale changes in social and emotional behavior. For example, patients with OFC lesions are reported to suffer from deficits in affective decision-making, including impaired emotional face and voice expression recognition (e.g., Hornak et al., 1996, 2003). However, previous studies have failed to acknowledge that emotional processing is a multistage process. Thus, different stages of emotional processing (e.g., early vs. late) in the same patient group could be affected in a qualitatively different manner. The present study investigated this possibility and tested implicit emotional speech processing in an ERP experiment followed by an explicit behavioral emotional recognition task. OFC patients listened to vocal emotional expressions of anger, fear, disgust, and happiness compared to a neutral baseline spoken either with or without lexical content. In line with previous evidence (Paulmann Kotz, 2008b), both patients and healthy controls differentiate emotional and neutral prosody within 200 ms (P200). However, the recognition of emotional vocal expressions is impaired in OFC patients as compared to healthy controls. The current data serve as first evidence that emotional prosody processing is impaired only at a late, and not at an early processing stage in OFC patients.