Document Detail

Compensatory motor control after stroke: an alternative joint strategy for object-dependent shaping of hand posture.
MedLine Citation:
PMID:  20457866     Owner:  NLM     Status:  MEDLINE    
Efficient grasping requires planned and accurate coordination of finger movements to approximate the shape of an object before contact. In healthy subjects, hand shaping is known to occur early in reach under predominantly feedforward control. In patients with hemiparesis after stroke, execution of coordinated digit motion during grasping is impaired as a result of damage to the corticospinal tract. The question addressed here is whether patients with hemiparesis are able to compensate for their execution deficit with a qualitatively different grasp strategy that still allows them to differentiate hand posture to object shape. Subjects grasped a rectangular, concave, and convex object while wearing an instrumented glove. Reach-to-grasp was divided into three phases based on wrist kinematics: reach acceleration (reach onset to peak horizontal wrist velocity), reach deceleration (peak horizontal wrist velocity to reach offset), and grasp (reach offset to lift-off). Patients showed reduced finger abduction, proximal interphalangeal joint (PIP) flexion, and metacarpophalangeal joint (MCP) extension at object grasp across all three shapes compared with controls; however, they were able to partially differentiate hand posture for the convex and concave shapes using a compensatory strategy that involved increased MCP flexion rather than the PIP flexion seen in controls. Interestingly, shape-specific hand postures did not unfold initially during reach acceleration as seen in controls, but instead evolved later during reach deceleration, which suggests increased reliance on sensory feedback. These results indicate that kinematic analysis can identify and quantify within-limb compensatory motor control strategies after stroke. From a clinical perspective, quantitative study of compensation is important to better understand the process of recovery from brain injury. From a motor control perspective, compensation can be considered a model for how joint redundancy is exploited to accomplish the task goal through redistribution of work across effectors.
Preeti Raghavan; Marco Santello; Andrew M Gordon; John W Krakauer
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, U.S. Gov't, Non-P.H.S.     Date:  2010-03-24
Journal Detail:
Title:  Journal of neurophysiology     Volume:  103     ISSN:  1522-1598     ISO Abbreviation:  J. Neurophysiol.     Publication Date:  2010 Jun 
Date Detail:
Created Date:  2010-06-10     Completed Date:  2010-09-09     Revised Date:  2013-05-29    
Medline Journal Info:
Nlm Unique ID:  0375404     Medline TA:  J Neurophysiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  3034-43     Citation Subset:  IM    
Department of Rehabilitation Medicine, Mount Sinai School of Medicine, 1450 Madison Avenue, Box 1240, New York, NY 10029, USA.
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MeSH Terms
Analysis of Variance
Feedback, Sensory / physiology*
Form Perception / physiology*
Hand / physiopathology*
Hand Strength / physiology
Joints / innervation,  physiopathology*
Middle Aged
Posture / physiology*
Psychomotor Performance / physiology
Stroke / pathology*,  physiopathology
Grant Support

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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