Bimanual coordination and limb-specific parameterization in patients with Parkinson's disease.

Bimanual coordination and the capability to parameterize the individual limb movements were examined in patients with Parkinson's disease (PD) as compared to healthy control subjects. In-phase and anti-phase patterns were performed while the individual limb movements were subjected to amplitude and loading manipulations. Findings showed that PD patients produced the bimanual configurations with lower degrees of phasing accuracy and consistency than control subjects, indicating an impairment at the global (coordinative) level of simultaneously produced movements. At the local (limb-specific) level, the imposed distances with and without loading were unaffected in PD patients as compared to control subjects, whereas cycle times were prolonged and depended on the task requirements. This illustrates a disturbance at the limb-specific level in complying with the execution of the submovements. The finding that movement slowness only became evident in the more complex conditions, suggests that it did not mainly represent a deficit in the execution of coordinated movements, but rather an inability to accommodate the motor output during stringent spatiotemporal task constraints.