Document Detail


The effect of bilateral isometric forces in different directions on motor cortical function in humans.
MedLine Citation:
PMID:  20668276     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The activity in the primary motor cortex (M1) reflects the direction of movements, but little is known about physiological changes in the M1 during generation of bilateral isometric forces in different directions. Here, we used transcranial magnetic stimulation to examine motor evoked potentials (MEPs), short-interval intracortical inhibition (SICI), and interhemispheric inhibition (IHI) in the left first dorsal interosseous (FDI) during isometric index finger abduction while the right index finger remained at rest or performed isometric forces in different directions (abduction or adduction) and in different postures (prone and supine). Left FDI MEPs were suppressed during bilateral compared with unilateral forces, with a stronger suppression when the right index finger force was exerted in the adduction direction regardless of hand posture. IHI targeting the left FDI increased during bilateral compared with unilateral forces and this increase was stronger during right index finger adduction despite the posture of the right hand. SICI decreased to a similar extent during both bilateral forces in both hand postures. Thus generation of index finger isometric forces away from the body midline (adduction direction), regardless of the muscle engaged in the task, down-regulates corticospinal output in the contralateral active hand to a greater extent than forces exerted toward the body midline (abduction direction). Transcallosal inhibition, but not GABAergic intracortical circuits, was modulated by the direction of the force. These findings suggest that during generation of bimanual isometric forces the M1 is driven by "extrinsic" parameters related to the hand action.
Authors:
Juliette A Yedimenko; Monica A Perez
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2010-07-28
Journal Detail:
Title:  Journal of neurophysiology     Volume:  104     ISSN:  1522-1598     ISO Abbreviation:  J. Neurophysiol.     Publication Date:  2010 Dec 
Date Detail:
Created Date:  2010-12-16     Completed Date:  2011-05-09     Revised Date:  2011-12-21    
Medline Journal Info:
Nlm Unique ID:  0375404     Medline TA:  J Neurophysiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  2922-31     Citation Subset:  IM    
Affiliation:
CNBC/Systems Neuroscience Institute, Department of Physical Medicine and Rehabilitation, 3501 Fifth Avenue, University of Pittsburgh, Pittsburgh, PA 15213, USA.
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MeSH Terms
Descriptor/Qualifier:
Adult
Electromyography
Evoked Potentials, Motor
Female
Fingers / physiology*
Humans
Isometric Contraction / physiology*
Male
Motor Cortex / physiology*
Prone Position
Pyramidal Tracts / physiology*
Supine Position
Transcranial Magnetic Stimulation
Young Adult
Grant Support
ID/Acronym/Agency:
R00 NS-06201/NS/NINDS NIH HHS

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


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