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Perturbations of human posture: influence of impulse modality on EMG responses and cerebral evoked potentials.
MedLine Citation:
PMID:  15136251     Owner:  NLM     Status:  PubMed-not-MEDLINE    
Abstract/OtherAbstract:
Leg muscle EMG responses and cerebral evoked potentials (CP), elicited by perturbations of stance while on a treadmill with split belts, were analyzed in order to study the relationship between compensatory leg muscle responses and afferent input to supraspinal centers. Various conditions of perturbation were used to establish the extent to which compensatory EMG responses and CPs show congruent behavior. Four different treadmill acceleration rates were applied in three different conditions (unilateral perturbation, directed forward or backward; bilateral perturbation, directed forward or backward; and opposing bilateral perturbation). EMG responses and CPs showed parallel increases in amplitude with increasing displacement velocity. The EMG responses showed distinct differences, predominantly in the response amplitude, between the different perturbation conditions, whereas the CPs were affected only to a minor degree. Tibialis anterior EMG responses were more closely related to the CP following forward perturbation than the corresponding gastrocnemius responses were to the CP following backward perturbation. We conclude that the EMG responses are more closely related than the CPs to displacement parameters and suggest that this is due to the further spinal processing of the afferent input needed to generate an appropriate EMG response. The closer relationship between the tibialis anterior response and CP may reflect a predominant central representation and control of tibialis anterior activation in the regulation of posture. The functional implications of these findings are discussed.
Authors:
V Dietz; G A Horstmann; W Berger
Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of motor behavior     Volume:  21     ISSN:  0022-2895     ISO Abbreviation:  J Mot Behav     Publication Date:  1989 Dec 
Date Detail:
Created Date:  2004-05-11     Completed Date:  2005-01-31     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0236512     Medline TA:  J Mot Behav     Country:  United States    
Other Details:
Languages:  eng     Pagination:  357-72     Citation Subset:  -    
Affiliation:
Department of Clinical Neurology and Neurophysiology, University of Freiburg, Federal Republic of Germany.
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