Objective: The purpose of this study was to determine whether one single auditory cue affected movement kinematics of more than one step in a sequential upper limb task in patients with Parkinson's disease.
Design: A counter-balanced repeated-measures design was employed. A total of 16 male patients with Parkinson's disease and 16 age-matched male and female controls performed the task under two conditions. In the signal-present condition, the participants were instructed to start the movement when they heard a bell ring. In the signal-absent condition, there was no bell ringing, and they were told to start the movement when they were ready. Kinematic performances for the first two movement segments (i.e., reaching for the pen and bringing the pen to the paper) were compared between conditions.
Results: The results indicated that the presence of the single auditory cue affected movement kinematics of the patients with Parkinson's disease but not that of the controls. When given external cueing, the patients elicited faster, more forceful, more efficient, more stable, but less smooth movement.
Conclusions: The results suggest that therapists should provide external cues according to their treatment goals. In addition, researchers should be aware of the influence of start signals when designing subsequent experiments.