Document Detail

Dissecting the mechanisms underlying short-interval intracortical inhibition using exercise.
MedLine Citation:
PMID:  21071618     Owner:  NLM     Status:  MEDLINE    
Recently, 2 physiologically distinct phases of short-interval intracortical inhibition (SICI) have been identified, a larger phase at interstimulus interval (ISI) 3 ms and a smaller phase at ISI 1 ms. While the former is mediated by synaptic processes, the mechanisms underlying the first phase of SICI remain a matter of debate. Separately, it is known that fatiguing hand exercise reduces SICI, a measure of cortical excitability. Consequently, the present study assessed effects of fatiguing hand exercise on the 2 SICI phases, using threshold tracking transcranial magnetic stimulation techniques, to yield further information on underlying mechanisms. Studies were undertaken on 22 subjects, with SICI assessed at baseline, after each voluntary contraction (VC) period of 120 s and 5, 10, and 20 min after last VC, with responses recorded over abductor pollicis brevis. Exercise resulted in significant reduction of SICI at ISI 1 ms (SICI(baseline) 9.5 ± 2.7%; SICI(MAXIMUM REDUCTION) 2.5 ± 2.5%, P < 0.05) and 3 ms (SICI(baseline) 16.8 ± 1.7%; SICI(MAXIMUM REDUCTION) 11.6 ± 2.1%, P < 0.05), with the time course of reduction being different for the 2 phases. Taken together, findings from the present study suggest that synaptic processes were the predominant mechanism underlying the different phases of SICI.
Steve Vucic; Benjamin C Cheah; Matthew C Kiernan
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't     Date:  2010-11-11
Journal Detail:
Title:  Cerebral cortex (New York, N.Y. : 1991)     Volume:  21     ISSN:  1460-2199     ISO Abbreviation:  Cereb. Cortex     Publication Date:  2011 Jul 
Date Detail:
Created Date:  2011-06-17     Completed Date:  2012-05-11     Revised Date:  2013-07-03    
Medline Journal Info:
Nlm Unique ID:  9110718     Medline TA:  Cereb Cortex     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1639-44     Citation Subset:  IM    
Department of Neurology, Sydney Medical School Westmead, University of Sydney, Sydney, NSW 2145, Australia.
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MeSH Terms
Evoked Potentials, Motor / physiology
Exercise / physiology*
Middle Aged
Motor Cortex / physiology*
Neural Inhibition / physiology*
Photic Stimulation / methods
Psychomotor Performance / physiology*
Time Factors
Transcranial Magnetic Stimulation / methods*
Young Adult

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

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