The neural correlates of decisions about sadness in facial expressions.

Models of decision processes postulate the action of a similar mechanism when computing responses across very different domains, such as decisions made on the intensity of a stimulus or according to subjective preferences. However, the neural substrates of decision-making in domains such as those involving emotion processing in social interactions have as yet remained largely unexplored. In this functional neuroimaging study, we used a paradigm developed in neuroeconomical studies of subjective preferences to uncover the neural substrates involved in deciding the degree of sadness in facial expressions, which convey information on sufferance in conspecifics. Because of the possible association of facial expressions with stimulus properties such as the capacity to be emotionally arousing, we used a procedure designed to control for this possible confound. The contrast representing differences in attributed sadness activated the precuneus and posterior cingular cortex, areas often implicated in studies of subjective preference. Also, the somatosensory cortex was active, an area associated with both sensory discrimination tasks in the visual domain and whose lesion is known to result in deficits in emotion recognition. In the same contrast, no activation of the amygdala, the substrate of emotional arousal, was detected (or of any other area associated with the sensory processing of faces, such as the fusiform gyrus). These results suggest that specific networks beyond those sensitive to the arousing properties of emotional stimuli are active when making choices in a social-cognitive domain.