Recurrent inhibition of wrist extensor motoneurones: a single unit study on a deafferented patient
In order to document the effects of recurrent inhibition on the firing times of human α-motoneurones during natural motor behaviour, a case study was performed on a deafferented patient. The fact that this subject had completely lost the large-diameter sensory afferents provided us with a unique op...
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Published in | The Journal of physiology Vol. 549; no. 3; pp. 975 - 984 |
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Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
Oxford, UK
The Physiological Society
15.06.2003
Blackwell Publishing Ltd Blackwell Science Inc |
Subjects | |
Online Access | Get full text |
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Summary: | In order to document the effects of recurrent inhibition on the firing times of human α-motoneurones during natural motor
behaviour, a case study was performed on a deafferented patient. The fact that this subject had completely lost the large-diameter
sensory afferents provided us with a unique opportunity of selectively stimulating the motor axons in the nerves. The tonic
activity of single motor units ( n = 21) was recorded in the extensor carpi radialis muscles while applying randomly timed antidromic electrical stimuli to
the radial nerve. The peristimulus time histogram analysis showed the presence of biphasic inhibitory effects, including an
early, short-lasting component followed by a longer-lasting component occurring 20â40 ms later. The interspike interval (ISI)
during which the stimulation occurred was generally lengthened as compared to the previous ISIs. The stimulation was most
effective when delivered early (20â30 ms) after a spike. It was also effective, although less so, when delivered at the end
of the ISI (70â100 ms after a spike). The lengthening effect sometimes extended over one or two of the subsequent ISIs. The
lengthening effect of the motor axon stimulation was followed by an excitatory-like effect, which took the form of a shortening
that affected up to five ISIs after the stimulation. The biphasic inhibitory effects and the subsequent facilitatory effects
are discussed in terms of the dual nature of the synaptic processes involved in the recurrent inhibitory network, the postactivation
facilitation/depression processes and the mutual inhibition occurring between Renshaw cells. |
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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.2003.039040 |