Document Detail

Myoelectric responses at flexors and extensors of human wrist to step torque perturbations.
MedLine Citation:
PMID:  7119855     Owner:  NLM     Status:  MEDLINE    
1. Torque-step perturbations were applied to flex or extend the wrists of normal human subjects. The electromyographic activity (EMG) of two of the stretched muscles, flexor carpi radialis and extensor carpi radialis, was monitored. 2. Based on functional characteristics and temporal bursting patterns, the EMG responses were partitioned into four distinct temporal intervals : 30-60, 60-120, 120-200, and greater than 200 ms after the onset of the torque step. The last interval continues for the duration of the step input: 200- 400 ms was chosen to represent activity in this interval. 3. EMG responses in the first two intervals show short, stable latencies and amplitudes that depend on the level of muscle contraction prior to the torque step. They are facilitated by any instruction requiring a reaction by the subject. They are reflexes that cannot be voluntarily suppressed by instruction to the subject. 4. The third EMG response is a triggered response. It is not a reflex because its appearance or absence is absolutely under voluntary control. Unlike true voluntary responses, there exists no dichotomy in responses latency or variability between known versus unknown directions of torque steps. 5. We consider that a truly voluntary response to a torque perturbation does not begin until about 200 ms after the step, which is on the order of visual or auditory reaction times. 6. The EMG responses were similar in both the wrist flexor and extensor studied. Ankle flexors and extensors do not show such similarity. 7. The EMG responses at the wrist and ankle are compared and shown to have many similarities. A general scheme for their classification is discussed.
R J Jaeger; G L Gottlieb; G C Agarwal
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Journal of neurophysiology     Volume:  48     ISSN:  0022-3077     ISO Abbreviation:  J. Neurophysiol.     Publication Date:  1982 Aug 
Date Detail:
Created Date:  1982-12-02     Completed Date:  1982-12-02     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0375404     Medline TA:  J Neurophysiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  388-402     Citation Subset:  IM    
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MeSH Terms
Auditory Perception / physiology
Muscles / physiology*
Reaction Time / physiology
Reflex, Stretch
Visual Perception / physiology
Wrist / physiology*
Grant Support

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

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