Control of aperture closure initiation during reach-to-grasp movements under manipulations of visual feedback and trunk involvement in Parkinson's disease

• Published in: Experimental brain research 2010-03, Vol.201 (3), p.509-525
• Main Authors: Rand, Miya Kato, Lemay, Martin, Squire, Linda M, Shimansky, Yury P, Stelmach, George E
• Format: Article
• Language: English
• Subjects: Aged; Aged, 80 and over; Arm - physiology; Basal ganglia; Biological and medical sciences; Biomechanical Phenomena; Biomedical and Life Sciences; Biomedicine; Cognition Disorders - etiology; Cognition Disorders - physiopathology; Degenerative and inherited degenerative diseases of the nervous system. Leukodystrophies. Prion diseases; Disability Evaluation; Feedback; Feedback, Sensory - physiology; Female; Fundamental and applied biological sciences. Psychology; Hand Strength - physiology; Humans; Kinematics; Male; Medical sciences; Middle Aged; Motor control and motor pathways. Reflexes. Control centers of vegetative functions. Vestibular system and equilibration; Movement Disorders - etiology; Movement Disorders - physiopathology; Muscle Contraction - physiology; Muscle, Skeletal - innervation; Muscle, Skeletal - physiopathology; Neurology; Neuropsychological Tests; Neurosciences; Parkinson Disease - physiopathology; Parkinson's disease; Photic Stimulation; Psychomotor Performance - physiology; Reaction Time - physiology; Research Article; Somatosensory Disorders - etiology; Somatosensory Disorders - physiopathology; Space Perception - physiology; Task Performance and Analysis; Time Factors; Vertebrates: nervous system and sense organs
• ISSN: 0014-4819; 1432-1106
• DOI: 10.1007/s00221-009-2064-2

The present project was aimed at investigating how two distinct and important difficulties (coordination difficulty and pronounced dependency on visual feedback) in Parkinson's disease (PD) affect each other for the coordination between hand transport toward an object and the initiation of finger closure during reach-to-grasp movement. Subjects with PD and age-matched healthy subjects made reach-to-grasp movements to a dowel under conditions in which the target object and/or the hand were either visible or not visible. The involvement of the trunk in task performance was manipulated by positioning the target object within or beyond the participant's outstretched arm to evaluate the effects of increasing the complexity of intersegmental coordination under different conditions related to the availability of visual feedback in subjects with PD. General kinematic characteristics of the reach-to-grasp movements of the subjects with PD were altered substantially by the removal of target object visibility. Compared with the controls, the subjects with PD considerably lengthened transport time, especially during the aperture closure period, and decreased peak velocity of wrist and trunk movement without target object visibility. Most of these differences were accentuated when the trunk was involved. In contrast, these kinematic parameters did not change depending on the visibility of the hand for both groups. The transport-aperture coordination was assessed in terms of the control law according to which the initiation of aperture closure during the reach occurred when the hand distance-to-target crossed a hand-target distance threshold for grasp initiation that is a function of peak aperture, hand velocity and acceleration, trunk velocity and acceleration, and trunk-target distance at the time of aperture closure initiation. When the hand or the target object was not visible, both groups increased the hand-target distance threshold for grasp initiation compared to its value under full visibility, implying an increase in the hand-target distance-related safety margin for grasping. The increase in the safety margin due to the absence of target object vision or the absence of hand vision was accentuated in the subjects with PD compared to that in the controls. The pronounced increase in the safety margin due to absence of target object vision for the subjects with PD was further accentuated when the trunk was involved compared to when it was not involved. The results