Document Detail

Effects of unexpected perturbations on trajectories and EMG patterns of rapid wrist flexion movements in humans.
MedLine Citation:
PMID:  2170870     Owner:  NLM     Status:  MEDLINE    
To investigate how motor programs can be modified by sensory inputs we recorded kinematic and EMG patterns from normal human subjects performing well-practised wrist flexion movements in response to an auditory tone. On random trials unexpected wrist perturbations were introduced at varying times after the signal to move had been given. Extension perturbations delivered before agonist EMG onset resulted in an increased maximum velocity (MV) during the wrist flexion movement and in an increased target overshoot even though the wrist was further from the target than expected by the subject at the onset of the movement. The first agonist EMG burst and the antagonist burst were both increased in magnitude in these perturbed trials. Flexion perturbations delivered before the agonist EMG onset moved the hand nearer to the target just prior to movement onset. These resulted in a reduced MV, but the expected increased target overshoot did not occur. The first agonist burst was reduced in magnitude, and the antagonist burst was increased in magnitude. Perturbations delivered after agonist EMG onset produced less change in the first agonist and antagonist EMG burst, and less compensation for the perturbation was evident in wrist position and velocity recordings. These results indicate that, at least in some situations, motor programs for rapid voluntary movements can be modified by afferent inputs. This interaction between central motor commands and sensory feedback might occur at the cortical or spinal level, depending on when perturbations occur relative to onset of EMG and movement. The timing of the EMG changes suggest that both reflex mechanisms and longer latency 'voluntary' adjustments contribute to the compensatory changes in movement trajectory.
R Hayashi; W J Becker; R G Lee
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Neuroscience research     Volume:  8     ISSN:  0168-0102     ISO Abbreviation:  Neurosci. Res.     Publication Date:  1990 Jun 
Date Detail:
Created Date:  1990-10-31     Completed Date:  1990-10-31     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  8500749     Medline TA:  Neurosci Res     Country:  IRELAND    
Other Details:
Languages:  eng     Pagination:  100-13     Citation Subset:  IM    
Department of Clinical Neurosciences, Faculty of Medicine, University of Calgary, Canada.
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MeSH Terms
Electric Stimulation
Median Nerve / physiology
Middle Aged
Movement / physiology*
Neural Conduction / physiology
Reaction Time / physiology
Wrist / physiology*

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