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Article: Modulation of an inhibitory reflex in single motor units in human masseter by tonic painful stimulation

TitleModulation of an inhibitory reflex in single motor units in human masseter by tonic painful stimulation
Authors
KeywordsMotor physiology
Muscle pain
Single motor units
Trigeminal reflexes
Issue Date1999
PublisherElsevier BV. The Journal's web site is located at http://www.elsevier.com/locate/pain
Citation
Pain, 1999, v. 83 n. 3, p. 441-446 How to Cite?
AbstractPerioral electrical stimuli cause inhibitory reflex responses in single motor-units (SMU) and surface electromyographic (EMG) recordings from voluntary contracted human jaw-closing muscles. Tonic experimental masseter pain has recently been shown to reduce the inhibitory reflex response in surface EMG recordings but the effect on SMU activity has not been described. In this study, motor-unit action potentials were recorded with wire electrodes inserted into the left masseter in eleven subjects. The subjects kept the SMU firing rate around 10 Hz by feedback. Ninety-nine electrical stimuli were applied sequentially to the left mental nerve with increasing stimulus delays in steps of 1 ms after the preceding motor unit action potential. The inhibitory reflex in SMU was recorded before, during and after infusion of hypertonic saline (5%) into the ipsilateral masseter muscle. Spike train data were used to calculate (1) the mean pre- and post-stimulus inter-spike-intervals (ISI) in all of the 99 trials, (2) cumulative changes in firing probability, and (3) estimation of the compound inhibitory post- synaptic potential (IPSP) in the masseter motoneuron. Tonic masseter pain did not change pre-stimulus SMU firing characteristics but the mean ISI for the first post-stimulus discharge (158.2 ± 9.2 ms) was significantly decreased compared to the pre-pain (175.8 ± 11.3 ms, P ≤ 0.05) and post-pain conditions (172.6 ± 11.6 ms, P ≤ 0.05). The post-stimulus firing probability was significantly increased and the relative amplitude of the estimated IPSP significantly decreased during tonic masseter pain compared to pre-pain and post-pain conditions. In conclusion, this study indicates that tonic masseter pain has a net excitatory effect on the inhibitory jaw- reflexes, which could be mediated by presynaptic mechanisms on the involved motoneurons.
Persistent Identifierhttp://hdl.handle.net/10722/67062
ISSN
2015 Impact Factor: 5.557
2015 SCImago Journal Rankings: 3.007
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorSvensson, Pen_HK
dc.contributor.authorMcMillan, ASen_HK
dc.contributor.authorGravenNielsen, Ten_HK
dc.contributor.authorWang, Ken_HK
dc.contributor.authorArendtNielsen, Len_HK
dc.date.accessioned2010-09-06T05:51:38Z-
dc.date.available2010-09-06T05:51:38Z-
dc.date.issued1999en_HK
dc.identifier.citationPain, 1999, v. 83 n. 3, p. 441-446en_HK
dc.identifier.issn0304-3959en_HK
dc.identifier.urihttp://hdl.handle.net/10722/67062-
dc.description.abstractPerioral electrical stimuli cause inhibitory reflex responses in single motor-units (SMU) and surface electromyographic (EMG) recordings from voluntary contracted human jaw-closing muscles. Tonic experimental masseter pain has recently been shown to reduce the inhibitory reflex response in surface EMG recordings but the effect on SMU activity has not been described. In this study, motor-unit action potentials were recorded with wire electrodes inserted into the left masseter in eleven subjects. The subjects kept the SMU firing rate around 10 Hz by feedback. Ninety-nine electrical stimuli were applied sequentially to the left mental nerve with increasing stimulus delays in steps of 1 ms after the preceding motor unit action potential. The inhibitory reflex in SMU was recorded before, during and after infusion of hypertonic saline (5%) into the ipsilateral masseter muscle. Spike train data were used to calculate (1) the mean pre- and post-stimulus inter-spike-intervals (ISI) in all of the 99 trials, (2) cumulative changes in firing probability, and (3) estimation of the compound inhibitory post- synaptic potential (IPSP) in the masseter motoneuron. Tonic masseter pain did not change pre-stimulus SMU firing characteristics but the mean ISI for the first post-stimulus discharge (158.2 ± 9.2 ms) was significantly decreased compared to the pre-pain (175.8 ± 11.3 ms, P ≤ 0.05) and post-pain conditions (172.6 ± 11.6 ms, P ≤ 0.05). The post-stimulus firing probability was significantly increased and the relative amplitude of the estimated IPSP significantly decreased during tonic masseter pain compared to pre-pain and post-pain conditions. In conclusion, this study indicates that tonic masseter pain has a net excitatory effect on the inhibitory jaw- reflexes, which could be mediated by presynaptic mechanisms on the involved motoneurons.en_HK
dc.languageengen_HK
dc.publisherElsevier BV. The Journal's web site is located at http://www.elsevier.com/locate/painen_HK
dc.relation.ispartofPainen_HK
dc.rightsPain. Copyright © Elsevier BV.en_HK
dc.subjectMotor physiologyen_HK
dc.subjectMuscle painen_HK
dc.subjectSingle motor unitsen_HK
dc.subjectTrigeminal reflexesen_HK
dc.titleModulation of an inhibitory reflex in single motor units in human masseter by tonic painful stimulationen_HK
dc.typeArticleen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=0304-3959&volume=83&spage=441&epage=446&date=1999&atitle=Modulation+of+an+inhibitory+reflex+in+single+motor+units+in+human+masseter+by+tonic+painful+stimulationen_HK
dc.identifier.emailMcMillan, AS: annemcmillan@hku.hken_HK
dc.identifier.authorityMcMillan, AS=rp00014en_HK
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1016/S0304-3959(99)00124-4en_HK
dc.identifier.pmid10568852-
dc.identifier.scopuseid_2-s2.0-0032701877en_HK
dc.identifier.hkuros49452en_HK
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-0032701877&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume83en_HK
dc.identifier.issue3en_HK
dc.identifier.spage441en_HK
dc.identifier.epage446en_HK
dc.identifier.isiWOS:000084152500007-
dc.publisher.placeNetherlandsen_HK
dc.identifier.scopusauthoridSvensson, P=7103121346en_HK
dc.identifier.scopusauthoridMcMillan, AS=7102843317en_HK
dc.identifier.scopusauthoridGravenNielsen, T=7005555610en_HK
dc.identifier.scopusauthoridWang, K=7501399229en_HK
dc.identifier.scopusauthoridArendtNielsen, L=7102885673en_HK

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