Voluntary emotional facial expressions in patients with focal cerebral lesions.

This study investigates the voluntary production of emotional facial expressions in 43 brain-damaged and 9 control subjects. The expressions of right- and left-hemisphere lesion groups did not differ significantly, but those of the anterior lesion group were impoverished relative to the posterior lesion and control groups. Deficits of voluntary expression were dissociable from impairments in "non-emotional" facial-motor functions, dysphasia, and unilateral neglect.