Skip Navigation

This Article
Right arrow FREE Full Text (PDF) Freely available
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrow Search for citing articles in:
ISI Web of Science (39)
Right arrowRequest Permissions
Right arrow Disclaimer
Google Scholar
Right arrow Articles by Alberts, J. L.
Right arrow Articles by Stelmach, G. E.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Alberts, J. L.
Right arrow Articles by Stelmach, G. E.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

Brain, Vol 121, Issue 4 725-742, Copyright © 1998 by Oxford University Press

ARTICLES

The co-ordination and phasing of a bilateral prehension task. The influence of Parkinson's disease

JL Alberts, JR Tresilian and GE Stelmach
Motor Control Laboratory, Arizona State University, Tempe 85283-0404, USA.

Parkinson's disease patients and control subjects performed a simultaneous bilateral reach-to-grasp task to two different sized objects and then pulled the two objects apart. The first phase of the task (reaching-to-grasp) allowed us to examine the issue that impairments in simultaneous movements for Parkinson's disease patients are seen in some tasks but not in others. It is suggested that the reason for this selective impairment is that Parkinson's disease compromises the ability to control multiple task-level degrees of freedom independently and concurrently (task-level degrees of freedom are defined as the number of independent parameters that require specification to perform the task). The first phase was used to test the hypothesis that Parkinson's disease results in a reduction of degrees of freedom that are independently controlled. It was predicted that Parkinson's disease patients would produce similar (homologous) movements of the two limbs (a symmetrical pattern) if the target objects have different accuracy requirements when they reach bilaterally to the two objects. For bilateral reaches for two different- size objects, only the control group showed reliably different patterns in the two limbs (asymmetrical pattern), while the Parkinson's disease group displayed a symmetrical pattern. These results provide support for the hypothesis that Parkinson's disease patients have a reduced capability to control multiple task-level degrees of freedom. The second phase of the task, which involved a transition from position control (reaching-to-grasp) to force control (stabilizing and pulling) was used to examine the ability of Parkinson's disease patients to make transitions between movement tasks and force control. In contrast to control subjects, Parkinson's disease patients produced staircase patterns for grip and load forces. Furthermore, a breakdown in the parallel co-ordination between grip and load force was observed for Parkinson's disease patients. These data suggest that Parkinson's disease disrupts the normal feedforward operations responsible for the co-ordination between grip and load forces.
Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?


This article has been cited by other articles:


Home page
 Neurorehabil Neural RepairHome page
A. L. Ridgel, J. L. Vitek, and J. L. Alberts
Forced, Not Voluntary, Exercise Improves Motor Function in Parkinson's Disease Patients
Neurorehabil Neural Repair, July 1, 2009; 23(6): 600 - 608.
[Abstract] [PDF]


Disclaimer: Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.