The programming and execution of movement sequences in Parkinson's disease.

Parkinsonian and neurologically normal subjects performed a finger-tapping task in which different sequence lengths had to be executed as rapidly as possible. For each response sequence, reaction time (RT), inter-tap-intervals (ITIs) and error patterns were recorded. It was found that the RT-sequence length relationship as well as the group ITI data were different for the two groups, indicative of impaired programming in the Parkinsonian subjects. This conclusion was supported by a relative dissociation of the first and subsequent taps and by a pattern of progressively increasing errors with longer tap sequences in the Parkinsonians.