1997 Fiscal Year Final Research Report Summary
Neural control of hyperactivity and spasm in the masticatory muscles.
| Project/Area Number |
07407053
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Functional basic dentistry
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| Research Institution | Osaka University |
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Principal Investigator |
MORIMOTO Toshifumi Osaka University Fac.Dent., Prof., 歯学部, 教授 (20028731)
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| Co-Investigator(Kenkyū-buntansha) |
HIDAKA Osamu Osaka Univ.Fac.Dent.Instructor, 歯学部, 助手 (30252696)
MASUDA Yuji Osaka Univ.Fac.Dent., Instructor, 歯学部, 助手 (20190366)
INOUE Tomio Osaka Univ.Fac.Dent., Assistant Prof., 歯学部, 講師 (70184760)
MATSUO Ryuji Osaka Univ.Fac.Dent., Associate Prof., 歯学部, 助教授 (30157268)
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| Project Period (FY) |
1995 – 1997
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| Keywords | spasm / muscle spindle / masticatory force / trigeminal motoneuron / biogenic amine / taste rejection behavior |
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| Research Abstract |
It is suggested that hyperactivity or spasm in the masticatory muscles cause the temporomandibular joint disorders. However the neural mechanism of the hyperactivity has not bee found clealy. To investigate this mechanism we have done following six experiments. (1) effect of the hardness of food on the control of masticatory force. (2) role of the muscle spindle afferents on the control of masticatory force. (3) modulation of jaw muscle spindle discharge during mastication in the awake animals (4) classification of the jaw muscle spindle afferents (5) influence of the biogenic amine on the membrane charactaristics of the trigeminal motoneurons (6) relationship between the taste rejection behavior and salivation.
Results were as follows :
(1) During cortically induced rhythmic jaw movements (CRJMs) in anesthetized rabbits, chewing of the harder test strips induced the larger EMG activities of the jaw closing muscle. (2) We observed the correlation between the magnitude of the masticatory force and the firing frequency of the spindle afferent of masticatory muscle. (3) The difference in the firing pattern among masticatory stages may be ascribed to a stage-dependent modulation of both fusimotor activity and jaw movement pattern. (4) We found the possibility that the jaw muscle spindle afferents may be calssified into two groups on the basis of the firing pattern in the response to the ramp-and-hold stretch. (5) Intracellular calcium concentration may modulate the effect of the biogenic amine on the afterdepolarization in the trigeminal motoneurons. (6) The parabrachial nucleus may play an important role on salivation induced by the rejectable taste.
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Research Products
(23 results)
