1997 Fiscal Year Final Research Report Summary
The difference pattern of regulation by muscle spindles during the various cortically-induced rhythmic movements.
| Project/Area Number |
08835013
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
咀嚼
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| Research Institution | Osaka University |
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Principal Investigator |
HIDAKA Osamu Osaka University, Fac.Dent., Instructor, 歯学部, 助手 (30252696)
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| Co-Investigator(Kenkyū-buntansha) |
MASUDA Yuji Osaka Univ.Fac.Dent., Instructor, 歯学部, 助手 (20190366)
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| Project Period (FY) |
1996 – 1997
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| Keywords | mastication / muscle spindle / rabbit / EMG / periodontal sensation |
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| Research Abstract |
To elucidate mechanisms of controlling masticatory force, we analyzed the discharges of spindle affertents in the mesencephalic trigeminal nucleus (MesV) simultaneously with masticatory muscle EMGs and jaw movements during cortically induced rhythmic jaw movements (CRJMs) in anesthetized rabbits. In addition, we investigated the onset of the difference between the EMG signals of both before and during the chewing of test strip. Five test strips of polyurethane foam of different hardness were prepared and inserted between the opposing molars during CRJMs. Similar recordings were made after deafferentation of periodontal and/or muscle sensations.
Results obtaind were as follows :
1. The integrated activity and duration of the masseteric EMG bursts also increased with strip hardness.
2. All recorded afferents dischrged rhythmically in reration to jaw movements, and the number of impulse during the jaw-closing phase increased with increasing the hardness of the materials.
3. The onset of the masseteric EMG response to the chewing of strip was evaluated, and it was occasionaly before the force onset or time lapse of the shortest latency for the jaw-stretch reflex.
4. In the early response (as described in 3), the behavior of the onset of the masseteric EMG response was as follows :
(1) It was not changed by strip hardness.
(2) It was not changed by the denervation of periodontal afferents.
(3) It was delayd by the deafferentation of muscle spindle afferents.
These results suggest that the muscle spindle activity is involved in the feedforward machanism during chewing.
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