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This experiment examined the preparation and the production of isometric force in Parkinson's disease (PD). PD patients, elderly, and young subjects generated force levels that were a percentage of their maximum (15, 30, 45, and 60%). Subjects were cued on the upcoming target force level and they were asked to produce the required response as fast as(More)
Previous research has shown that subjects can adapt with either arm to an opposite visual distortion, and the two adaptive states can then be used in sequence to control the respective arm. To extend this finding, we exposed the left and right arms of our subjects to opposite-directed rotations of the visual field alternately for 20 s each, and determined(More)
The control of unimanual and bimanual aiming movements by Parkinson's disease and control subjects was examined. Despite greater bimanual movement initiation asynchrony and overall bradykinesia, the Parkinson's disease subjects were affected by the experimental manipulations in the same way as controls. Symmetrical and, more especially, asymmetrical(More)
An experiment is reported which examined whether gravitational torque acting about a joint is used by the CNS in elbow joint angle matching. Subjects were required to match the joint angles of their two limbs while the external torques acting about each elbow were systematically varied. It was found that when the matching limb was differentially loaded, the(More)
Subjects with Parkinson's disease (PD) and age-matched controls performed an isometric force production task, aiming at different target force levels without concurrent force feedback. Overall, PD subjects were as accurate as controls in attaining the target force levels, but executed the task differently. They had longer times to peak force and contraction(More)
The effects of advance information on movement planning in parkinsonism were assessed by means of movement precuing. Using this technique, the response latencies of identical sets of movements were compared across conditions in which the degree and type of advance movement information were manipulated. Specifically, prior information concerning three(More)
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(More)
Two experiments were performed to determine if proprioceptive signals are perceived more readily in terms of limb segment inclinations to the vertical than as joint angles. Subjects attempted to match arm positions with the upper arms supported at different inclinations. Constant error data showed that, when instructed to match forearm inclinations to the(More)
OBJECTIVES The primary aim of this study was to determine how Parkinson's disease (PD) affects driving performance. It also examined whether changes in driver safety were related to specific clinical disease markers or an individual's self rating of driving ability. METHODS The driving performance of 25 patients with idiopathic PD and 21 age matched(More)
BACKGROUND Falls are a major health and injury problem for people with Parkinson disease (PD). Despite the severe consequences of falls, a major unresolved issue is the identification of factors that predict the risk of falls in individual patients with PD. The primary aim of this study was to prospectively determine an optimal combination of functional and(More)