Illusion caused by vibration of muscle spindles reveals an involvement of muscle spindle inputs in regulating isometric contraction of masseter muscles
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- Taisuke Tsukiboshi
- Department of Neuroscience and Oral Physiology, Osaka University Graduate School of Dentistry, Suita, Osaka, Japan;
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- Hajime Sato
- Department of Neuroscience and Oral Physiology, Osaka University Graduate School of Dentistry, Suita, Osaka, Japan;
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- Yuto Tanaka
- Department of Neuroscience and Oral Physiology, Osaka University Graduate School of Dentistry, Suita, Osaka, Japan;
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- Mitsuru Saito
- Department of Neuroscience and Oral Physiology, Osaka University Graduate School of Dentistry, Suita, Osaka, Japan;
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- Hiroki Toyoda
- Department of Neuroscience and Oral Physiology, Osaka University Graduate School of Dentistry, Suita, Osaka, Japan;
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- Toshifumi Morimoto
- Department of Neuroscience and Oral Physiology, Osaka University Graduate School of Dentistry, Suita, Osaka, Japan;
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- Kemal Sitki Türker
- Koç University School of Medicine, Istanbul, Turkey
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- Yoshinobu Maeda
- Department of Removable Prosthodontics, Osaka University Graduate School of Dentistry, Suita, Osaka, Japan; and
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- Youngnam Kang
- Department of Neuroscience and Oral Physiology, Osaka University Graduate School of Dentistry, Suita, Osaka, Japan;
書誌事項
- 公開日
- 2012-11-01
- 資源種別
- journal article
- DOI
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- 10.1152/jn.00997.2011
- 公開者
- American Physiological Society
この論文をさがす
説明
<jats:p> Spindle Ia afferents may be differentially involved in voluntary isometric contraction, depending on the pattern of synaptic connections in spindle reflex pathways. We investigated how isometric contraction of masseter muscles is regulated through the activity of their muscle spindles that contain the largest number of intrafusal fibers among skeletal muscle spindles by examining the effects of vibration of muscle spindles on the voluntary isometric contraction. Subjects were instructed to hold the jaw at resting position by counteracting ramp loads applied on lower molar teeth. In response to the increasing-ramp load, the root mean square (RMS) of masseter EMG activity almost linearly increased under no vibration, while displaying a steep linear increase followed by a slower increase under vibration. The regression line of the relationship between the load and RMS was significantly steeper under vibration than under no vibration, suggesting that the subjects overestimated the ramp load and excessively counteracted it as reflected in the emergence of bite pressure. In response to the decreasing-ramp load applied following the increasing one, the RMS hardly decreased under vibration unlike under no vibration, leading to a generation of bite pressure even after the offset of the negative-ramp load until the vibration was ceased. Thus the subjects overestimated the increasing rate of the load while underestimating the decreasing rate of the load, due to the vibration-induced illusion of jaw opening. These observations suggest that spindle Ia/II inputs play crucial roles both in estimating the load and in controlling the isometric contraction of masseter muscles in the jaw-closed position. </jats:p>
収録刊行物
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- Journal of Neurophysiology
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Journal of Neurophysiology 108 (9), 2524-2533, 2012-11-01
American Physiological Society
