1992 Fiscal Year Final Research Report Summary
Central neural mechanisms responsible for correlation of mastication with excitability of spinal reflex
| Project/Area Number |
03454426
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Functional basic dentistry
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| Research Institution | Tokyo Medical and Dental University |
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Principal Investigator |
NAKAMURA Yoshio Professor Department of Physiology Faculty of Dentistry, Tokyo Medical and Dental University, 歯学部, 教授 (10010026)
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| Project Period (FY) |
1991 – 1992
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| Keywords | Crural muscles / Monosynaptic reflex / Masticatory movements / Fictive mastication / Facilitation / Non-reciprocal / Motoneuron / Postsynaptic excitation |
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| Research Abstract |
1.Modulation of H reflex of the soleus muscle was studied during gum-chewing and rhythmical jaw-opening and closing movements without contact of upper and lower teeth in 5 healthy adult male subjects. We found (1) that the amplitude of the H reflex increased tonically throughout either of the rhythmical jaw movements, and (2) that there was no significant difference in the increase in reflex amplitude between the jaw-closing and - opening phases. It was concluded (1) that the soleus H reflex is tonically facilitated during mastication and (2) that afferent impulses from intraoral mechanoreceptors are not indispensable for the facilitation.
2. Mode of facilitation of H reflex of crural muscles during mastication and the central neural mechanisms underlying the facilitation were studied in urethane-anesthetized rabbits. Two pairs of bipolar silver-wire electrodes were fixed to the tibial nerve innervating crural extensors and the common peroneal nerve innervating crural flexors, respectiv
… More
ely. Monosynaptic reflex volleys (efferent activities eliciting H reflex) evoked by stimulation of either nerve with the proximal electrodes were recorded with the distal electrodes. Modulation of the reflex discharges was studied during masticatory movements induced by repetitive stimulation of the cortical masticatory area (CMA). (1) The reflex volleys recorded from either nerve tonically increased in amplitude during CMA-induced actual and ficitvie masticatory movements, with no significant difference between jaw-opening and-closing phases. (2) Antidromic field potentials in the anterior horn of the lumbar cord evoked by either the tibial or common peroneal nerve increased during actual and fictive mastication. It was concluded (1) that H reflex of crural muscles undergoes a tonic non-reciprocal facilitation during mastication, (2) that intraoral mechanoreceptive afferents are not essential for the facilitation, and (3) that an increase in excitability of motoneurons is involved in the facilitation of the H reflex during mastication. Less
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