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Voluntary motor commands in human ballistic movements
Author(s) -
Desmedt John E.,
Godaux E.
Publication year - 1979
Publication title -
annals of neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.764
H-Index - 296
eISSN - 1531-8249
pISSN - 0364-5134
DOI - 10.1002/ana.410050503
Subject(s) - isometric exercise , proprioception , motor unit , isotonic , index finger , dorsum , physical medicine and rehabilitation , physics , control theory (sociology) , anatomy , neuroscience , psychology , computer science , medicine , control (management) , physical therapy , artificial intelligence
The integrated electromyogram of the first dorsal interosseous muscle in normal humans presents a brief early burst in voluntary ballistic abduction of the index finger. Unexpected decrease in torque load does not change the burst. By contrast, in fast ramp abduction with a time‐to‐peak of 0.5 second, the electromyographic activity is fairly continuous up to the peak displacement, and it is silenced with a delay of 50 msec by unexpected unloading. Thus fast ramp, but not ballistic, voluntary contractions are under current long loop control from proprioceptive input. In a second set of experiments, the analysis of single motor unit potentials with highly selective electrodes in interosseous muscle indicated that ballistic thresholds are smaller than ramp thresholds under either isotonic or isometric conditions. However, the recruitment rank of the motor units was identical in finger abductions carried out in either ramp or ballistic modes.