Hemiregional facial asymmetry in expression of emotion: a concept needs to be verified.

In most of the neuropsychological studies the left-right hemifacial asymmetry during expression of emotion has been reported, although the present author proposed a concept of hemiregional asymmetry and reported that greater left hemifacial involvement was specific to the lower region of the face and greater right hemifacial was specific to the upper region of the face. It is speculated that this differential hemifacial involvement is a function of the right hemisphere, and it is explained in terms of neural innervation to facial muscles. This speculation needs to be verified further to arrive at a general conclusion.