Document Detail

Disturbances of motor output in a cat hindlimb muscle after acute dorsal spinal hemisection.
MedLine Citation:
PMID:  3169170     Owner:  NLM     Status:  MEDLINE    
Force and electromyogram (EMG) responses of the medial gastrocnemius muscle were assessed during isometric contractions in 8 decerebrate cat preparations, before and after acute dorsal hemisection of the spinal cord at the T12 level. The measures derived included the relation between static force and mean rectified EMG, the EMG amplitude distribution, EMG power spectral density, and force power spectral density. Our findings were that the spinal lesion induced modifications in the shape of the EMG amplitude distribution, a substantial increase in mean rectified EMG per unit force, and increases in EMG spectral power and force spectral power over a broad band of frequencies. In 7/8 preparations, there was disproportionate enhancement of EMG spectral power below 40 Hz, with a commensurate reduction in the EMG mean power frequency (MPF) in 6 of these 7 cases. Recordings of motoneuron discharge from 9 decerebrate preparations taken before and after the spinal hemisection revealed that the lesion-induced changes in EMG and force power spectra were accompanied by lower mean discharge rates, and by a compression of the range of recruitment force. These changes in motoneuron rate and recruitment were probably responsible for the changes in EMG and force measures, especially for the relative increase in low-frequency EMG power. If these acute disturbances of motoneuron rate and recruitment persist in chronic human neurological disorders, they represent an important and largely unrecognized source of muscular weakness and increased fatigability.
M J Blaschak; R K Powers; W Z Rymer
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Experimental brain research     Volume:  71     ISSN:  0014-4819     ISO Abbreviation:  Exp Brain Res     Publication Date:  1988  
Date Detail:
Created Date:  1988-11-03     Completed Date:  1988-11-03     Revised Date:  2013-12-13    
Medline Journal Info:
Nlm Unique ID:  0043312     Medline TA:  Exp Brain Res     Country:  GERMANY, WEST    
Other Details:
Languages:  eng     Pagination:  377-87     Citation Subset:  IM    
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MeSH Terms
Action Potentials
Hindlimb / innervation*,  physiology
Motor Neurons / physiology*
Muscle Contraction*
Muscles / innervation*,  physiology
Spinal Cord / physiology*

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