Perturbation of the grasp component of a prehension movement in a subject with hemiParkinson's disease.

The response to perturbation of the manipulation component during prehension was assessed for both hands of a hemiParkinson and of a Control subject. With perturbed trials, the hemiParkinson showed the same pattern as the Control: a reorganization of kinematic parameters and no increase of movement time. However, for both limbs of the hemiParkinson subject there was a transition phase from precision grip to whole hand prehension--this was more pronounced for the affected limb. The manipulation component did not show a delay of activation [2]. Thus the global dysfunction in the performance of sequential movement patterns was related to aspects of task predictability.