Overt and covert processing of emotion from identity in the brain
Face identity affords emotional information by means of poorly understood brain mechanisms. This information is important in social interactions (i.e. when distinguishing friends from enemies). Here we measured, through functional magnetic resonance imagining, the brain activity elicited by familiar faces with different degrees of emotional significance in typical observers as well as in a patient with lesions encompassing both fusiform cortices (crucial for face processing). The patient suffered from severely impaired recognition of face identity (prosopagnosia). Two types of brain areas responding to highly familiar faces were evinced in typical observers, those with larger activations for emotionally significant faces (orbitofrontal cortex) and those indifferent to this significance (occipital face area). Surprisingly, despite his impaired identification of faces, both types of area were more activated by familiar- than unfamiliar faces in the patient. This implies alternative routes for face processing that bypass the fusiform areas and can function outside of consciousness.