Document Detail

Changes in perceived heaviness and motor commands produced by cutaneous reflexes in man.
MedLine Citation:
PMID:  3411508     Owner:  NLM     Status:  MEDLINE    
1. This study examined the relationship between the perceived heaviness of a weight and reflexes acting on the motoneurones required for the contraction. The perceived heaviness of low (100 g) and high (500 g) reference weights lifted by the first dorsal interosseous muscle was estimated using a matching task. Weights were also lifted during stimulation of the digital nerves of the index finger at two times and four times sensory threshold (T). Averages of force and EMG were also made when isometric forces of 100 and 500 g were maintained. 2. Stimuli at 4T produced a significant increase in perceived heaviness in each subject for both reference weights. Averages of EMG made under isometric conditions showed a short-latency inhibition with a reflex reduction in force following single stimuli. This inhibition was also observed during weight lifting when trains of stimuli were given. 3. Stimuli at 2T produced less-marked changes in EMG, averaged force, and perceived heaviness for individual subjects. However, for the group of subjects, perceived heaviness declined significantly with 2T stimuli for the 500 g but not the 100 g weight. This decrease in perceived heaviness was associated with evidence of short-latency facilitation within the motoneurone pool. 4. Inhibition of the motoneurone pool was associated with an increase and facilitation with a decrease in perceived heaviness. These observations favour a role for a signal of centrally generated motor command in the sensation of heaviness and provide insight as to how this signal must change when reflex inputs change and when high-threshold motoneurones are recruited.
A M Aniss; S C Gandevia; R J Milne
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Journal of physiology     Volume:  397     ISSN:  0022-3751     ISO Abbreviation:  J. Physiol. (Lond.)     Publication Date:  1988 Mar 
Date Detail:
Created Date:  1988-10-13     Completed Date:  1988-10-13     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  0266262     Medline TA:  J Physiol     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  113-26     Citation Subset:  IM; S    
Department of Neurology, Prince Henry Hospital, School of Medicine, University of New South Wales, Sydney, Australia.
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MeSH Terms
Action Potentials
Fingers / physiology
Motor Neurons / physiology*
Muscle Contraction
Reflex / physiology*
Sensory Thresholds / physiology
Skin / innervation*
Weight Perception / physiology*

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