Document Detail

Task-and phase-related changes in cortico-muscular coherence.
MedLine Citation:
PMID:  18382125     Owner:  NLM     Status:  MEDLINE    
Cortico-muscular coherence was compared during ramp-and-hold isometric and quasi-isotonic contraction of the ankle joint in human subjects. EEG was recorded from the leg area of the motor cortex. EMG was recorded from the tibialis anterior (TA) muscle. The subjects were requested to maintain a steady low level of dorsiflexion and at intervals of 10 s to increase the contraction level within 1 s, maintain this level for 4 s and then decrease the level of contraction again within another 1 s. In seven subjects coherence in the 15-35 Hz frequency band was seen between EEG and TA EMG during low-level tonic dorsiflexion. In all subjects coherence disappeared during the ramp phase for both isometric and quasi-isotonic contraction. Coherence at other frequencies was also not observed in any of the subjects during the ramp phase. During the hold phase at the stronger level of contraction coherence reappeared quickly and had the same size as at the low level of contraction. However, a significantly larger level of coherence was found during quasi-isotonic than during the isometric contraction. This demonstrates that cortico-muscular coherence in the 15-35 Hz frequency band is phase- and task-related. The decrease in 15-35 Hz coherence during the ramp phase may be related to event-related desynchronization of EEG activity. The larger level of coherence during quasi-isotonic contraction may reflect a higher demand of precise control of the joint position. It may also reflect a greater need for binding of functionally related cortical pyramidal tract neurons.
Yoshihisa Masakado; Jens Bo Nielsen
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Keio journal of medicine     Volume:  57     ISSN:  0022-9717     ISO Abbreviation:  Keio J Med     Publication Date:  2008 Mar 
Date Detail:
Created Date:  2008-04-02     Completed Date:  2008-06-09     Revised Date:  2008-08-07    
Medline Journal Info:
Nlm Unique ID:  0376354     Medline TA:  Keio J Med     Country:  Japan    
Other Details:
Languages:  eng     Pagination:  50-6     Citation Subset:  IM    
Keio University Tsukigase Rehabilitation Center, Shizuoka, Japan.
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MeSH Terms
Isometric Contraction / physiology*
Models, Biological
Motor Cortex / physiology*
Muscle, Skeletal / innervation,  physiology*

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