Although we have learned much about the neuropsychological control of facial expressions of emotion, there is still much work to do. We suggest that future work integrate advances in our theoretical understanding of the roles of volition and consciousness in the elicitation of emotion and the production of facial expressions with advances in our understanding of its underlying neurophysiology. We first review the facial musculature and the neural paths thought to innervate it, as well as previous attempts at understanding the (...) neural control of facial expressions of emotion, focusing on the voluntary-involuntary dichotomy and studies of hemispheric specialization. In the second section, we discuss four major aspects of the psychology of facial expressions of emotion that have particular import to their neurophysiological substrates. We offer these as a starting point for a better integration of psychological and neurophysiological perspectives in considering the neuropsychological control of facial expressions of emotion. (shrink)

Darwin discusses why different muscles are brought into action under different emotions and how particular animals have adapted for association with man.