Programming of single movements in Parkinson's disease: comparison with Huntington's disease.

The preparation of individual finger movements was examined in Parkinson's disease (PD), in comparison with a similar study of Huntington's disease (HD). Motor programming was varied by increasing the amount of information available in advance of each movement. PD patients had particular difficulty when there was no cue light in advance of the movement, and when two upcoming movements were cued ahead of the current movement. Such difficulties suggest that PD patients may have difficulty in performing movements without sensory cuing, and in maintaining and organising a future sequence of movements. HD patients had been previously shown to have similar deficits. Commonalities in these once contrasted disorders probably arise from disruption of common mechanisms.