Changes in perceived heaviness and motor commands produced by cutaneous reflexes in man
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 mat...
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Published in | The Journal of physiology Vol. 397; no. 1; pp. 113 - 126 |
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Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
Oxford
The Physiological Society
01.03.1988
Blackwell |
Subjects | |
Online Access | Get full text |
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Summary: | 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. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0022-3751 1469-7793 |
DOI: | 10.1113/jphysiol.1988.sp016991 |