Hand preshaping in Parkinson's disease : effects of visual feedback and medication state

• Published in: Experimental brain research Vol. 168; no. 1-2; pp. 186 - 202
• Main Authors: SCHETTINO, Luis F, ADAMOVICH, Sergei V, HENING, Wayne, TUNIK, Eugene, SAGE, Jacob, POIZNER, Howard
• Format: Journal Article
• Language: English
• Published: Berlin Springer 01.01.2006; Springer Nature B.V
• Subjects: Aged; Analysis of Variance; Antiparkinson Agents - therapeutic use; Biological and medical sciences; Case-Control Studies; Degenerative and inherited degenerative diseases of the nervous system. Leukodystrophies. Prion diseases; Dopamine - metabolism; Feedback; Female; Fundamental and applied biological sciences. Psychology; Hand - physiopathology; Hand Strength - physiology; Humans; Male; Medical sciences; Middle Aged; Motor control and motor pathways. Reflexes. Control centers of vegetative functions. Vestibular system and equilibration; Movement - physiology; Neurology; Parkinson Disease - physiopathology; Parkinson Disease - therapy; Psychomotor Performance - drug effects; Psychomotor Performance - physiology; Time Factors; Vertebrates: nervous system and sense organs; Vision, Ocular - drug effects; Vision, Ocular - physiology; Human; Gripping; Nervous system diseases; Guide; Parkinson's disease; Hand preshaping; Proprioception; Deficiency; Grasping; Parkinson disease; Dopamine-replacement therapy; Hand; Cerebral disorder; Sensorimotor coordination; Modulation; Central nervous system disease; Bradykinesia; Degenerative disease; Visuomotor control; Visual task; Extrapyramidal syndrome
• ISSN: 0014-4819; 1432-1106
• DOI: 10.1007/s00221-005-0080-4

Previous studies in our laboratory examining pointing and reach-to-grasp movements of Parkinson's disease patients (PDPs) have found that PDPs exhibit specific deficits in movement coordination and in the sensorimotor transformations required to accurately guide movements. We have identified a particular difficulty in matching unseen limb position, sensed by proprioception, with a visible target. In the present work, we further explored aspects of complex sensorimotor transformation and motor coordination using a reach-to-grasp task in which object shape, visual feedback, and dopaminergic medication were varied. Normal performance in this task requires coordinated generation of appropriate reach, to bring the hand to the target, and differentiated grasp, to preshape the hand congruent with object form. In Experiment 1, we tested PDPs in the off-medication state. To examine the dependence of subjects on visual feedback and their ability to implement intermodal sensory integration, we required them to reach and grasp the target objects in three conditions: (1) Full Vision, (2) Object Vision with only the target object visible and, (3) No Vision with neither the moving arm nor the target object visible. PDPs exhibited two types of deficits. First, in all conditions, they demonstrated a generalized slowing of movement or bradykinesia. We consider this an intensive deficit, since it involves largely a modulation of the gain of specific task parameters: in this case, velocity of movement. Second, they were less able than controls to extract critical proprioceptive information and integrate it with vision in order to coordinate the reach and grasp components of movement. These deficits which involve the coordination of different inputs and motor components, we classify as coordinative deficits. As in our previous work, the PDPs' deficits were most marked when they were required to use proprioception to guide their hand to a visible target (Object Vision condition). But even in the full-vision condition, their performance only became fully accurate when both the target and effector (hand) were simultaneously visible. In Experiment 2, PDPs were tested on their dopaminergic replacement therapy. Dopaminergic treatment significantly ameliorated the bradykinesia of the PDPs, but produced no changes in the hand preshaping deficiencies of PDPs. These results suggest that adequate treatment of the PDPs may more readily compensate for intensive, than coordinative deficits, since the latter are likely to depend on specific and time-dependent neural interdependencies that are unlikely to be remediated simply by increasing the gain of a pathway.