Emotional facial expression in Parkinson's disease: A response to Bowers (2006)

Bowers et al. (2006) cite my 1984 review of the neuropsychology of facial expression (Rinn, 1984) as “the underlying impetus” for their recent investigation of facial expression in Parkinson's disease (PD). In that paper, I noted that impaired basal ganglia function in PD results in diminished spontaneous expressive facial movements, yet it produces no true paralysis for volitionally induced facial movements. Bowers et al. take my statements a step further: “According to Rinn (1984), patients with Parkinson's disease (PD) have little difficulty posing facial emotions when explicitly told to do so. They just fail to do so spontaneously.” They also quote me as describing Parkinson's disease as “the ‘model system’ for subcortical, basal ganglia influences on facial expression.” Bowers then goes on to demonstrate that the facial expression deficiencies of PD patients are not confined to a lack of spontaneous emotional movements (the masked face), and that volitionally posed facial expressions in PD are also aberrant [i.e., slow (bradykinesic) and of diminished amplitude].