Sensorimotor control in Parkinsonism.

Performance on two sensorimotor tasks was compared between 28 patients with Parkinsonism and 28 age and sex matched controls. One task involved complex motor activity (the Bead and Tapper test) and the other simple motor activity with a verbal component (the Letter Cancellation test). Both tests had three levels of complexity. Under conditions of increasing complexity in the performance required, the scores for the Parkinsonism subjects decreased disproportionately compared with the controls. This finding was more clearly established for the Bead and Tapper test than for the Letter Cancellation test. These results confirmed previous studies, and the nature of a possible central programming deficit was discussed. Laterality of brain involvement in the Parkinsonism subjects had no significant effect.