運動学、筋電図 Kinematics and EMG
P1-1-65 赤核刺激による2種類の開口反射への効果 Effects of two types of jaw-opening reflexes by stimulation of the red nucleus ○佐藤義英1, 矢島絵理子2, 石塚健一1, 長峯康博2, 岩崎信一1 ○Yoshihide Satoh1, Eriko Yajima2, Ken'Ichi Ishizuka1, Yasuhiro Nagamine2, Shin-ichi Iwasaki1 日本歯科大・新潟生命歯・生理1, 日本歯科大・新潟生命歯・矯正2 Dept Physiol, Nippon Dental Univ, Niigata1, Dept Orthodon, Nippon Dental Univ, Niigata2 The red nucleus (RN) is cytoarchitecturally divided into two parts; the parvicellular part (RNP) and the magnocellular part (RNM). Our previous papers showed that stimulation of the RN facilitated the jaw-opening reflex (JOR) evoked by innocuous stimulus and suppressed the JOR evoked by noxious stimulus. The stimulus conditions of the RN, however, were different in those studies. The present study aimed to (1) compare the effects of RNM or RNP stimulation between low- and high-threshold afferent-evoked JORs, and (2) compare the largeness of the effects between the RNP and the RNM. The experiments were performed on anesthetized rats. The test stimulation was applied to the inferior alveolar nerve (IAN) (1 pulse, 0.1 ms in duration, 1 Hz) to evoke the JOR. The stimulus intensity was either 1.2 (low threshold) or 4.0 (high threshold) times the threshold. The electromyograms were recorded from the anterior belly of the digastric muscles. The conditioning stimulation (1pulse, 0.2 ms in duration, 1 Hz, 100 &muA) was applied to the RNM or the RNP. Additionally, localized microinjections of glutamate were made into the RNM or the RNP. Electrical and chemical stimulation of the RN significantly facilitated the JOR evoked by test low-threshold IAN stimulation. Significant facilitation was observed at a conditioning-test interval of 5-18 ms. The facilitation was observed at 2-10 min after microinjection of glutamate. On the other hand, electrical and chemical stimulation of the RN significantly suppressed the JOR evoked by test high-threshold IAN stimulation. Significant suppression was observed at a conditioning-test interval of 20-40 ms. The suppression was observed at 10-15 min after microinjection of glutamate. The facilitatory effect was not different between the RNM and the RNP. The suppressive effect of the RNM, however, was significantly larger than that of the RNP. These results suggest that the RN has different functional role on the control of the JOR.	P1-1-66 嚥下体操は飲水に必要な筋活動を軽減する Enge-Taisou: upper-body exercise reduces muscle load with swallowing ○植田晃弘1, 小野弓絵1, 小松知子2, 李昌一3 ○Akihiro Ueta1, Yumie Ono1, Tomoko Komatu2, Masaiti Ri3 明治大院・理工・電気1, 神歯大・歯・障害者歯科2, 神歯大・歯・薬理3 Grad.Sch of .Sci & Tech Meiji Univ, Kanagawa1, Div. of Dent. for Special Patients, Dept. of Clin. Care Med., Kanagawa Dent. Col., Kanagawa, Japan2, Div. of Pharm. and ESR Lab., Dept. of Clin. Care Med., Kanagawa Dent. Col., Kanagawa, Japan3 Improving the ability of oral ingestion is important to maintain the quality of life of the elderly people. The 'Enge-Taisou', the upper-body exercise developed by dentists and care workers in Japan, is currently adopted in many nursing homes for the elderly to prevent or relieve the dysphagia, although the quantitative and physiological evaluation of this exercise has not been available yet. We therefore used surface electromyogram (EMG) to investigate the acute effect of the exercise on the swallowing muscles activity. Twenty young-adult subjects (11 male and 9 female, mean age 23.5±4.2) without any problem with swallowing participated in the experiment. They performed two sessions of water swallow test (gulping 15 ml of water), between which they carried out the exercise with video instructions. The exercise consisted of a sequence of deep breathing, stretching of the muscles in the head, neck, shoulders, tongue and perioral regions, and vocalizing plosive sounds, all of which continued for approximately 5 min. We recorded EMG during water intake from the masseter, the genioglossus, the mylohyoid, and the infrahyoid muscles (IM) on the left side using wireless EMG system. All EMG signals were rectified and low-pass filtered at 5 Hz (rfEMG). We compared the maximum amplitudes and the durations of the rfEMG signals before and after the exercise. We found that 17 of 20 subjects showed decrease in either the maximum amplitude or the duration of the IM activity after the exercise. Subjects whose maximum amplitude and duration of IM activity decreased demonstrated concurrent decrease in those of the mylohyoid and the masseter muscles after the exercise, respectively. There was no gender difference in the effect of the exercise, although the amplitudes of the muscle activity were larger in male subjects throughout the experiment. These results suggest the feasibility of this exercise to help smooth swallowing.
P1-1-67 筋電信号からの筋制御方策の定量化モデル Quantitative evaluation model of the muscle control policy with EMG signal ○閔庚甫1, 辛徳2, 李鍾昊1, 筧慎治1 ○Kyuengbo Min1, Duk Shin2, Jongho Lee1, Shinji Kakei1 東京都医学総合研究所1, 東京工業大学2 Tokyo Metropolitan Institute of Medical Science, Tokyo1, Tokyo Institute of Technology, Yokohama2 Human motion is controlled with multiple muscles. As the number of muscles is much larger than the total degrees of freedoms of joints, each degree of freedom is controlled with multiple muscles. Furthermore, some muscles are active to control two degrees of freedom as bi-articular muscles. Due to the redundant nature of the musculo-skeletal system, while highly flexible control solutions are available for the brain, it needs to reduce the excess degrees of freedom to get a unique solution. To overcome this redundancy, it is generally assumed that the brain recruits muscles as synergies, functional sets of muscles. Here we propose a model that extracts this control mechanism from EMG signals of multiple muscles. We presume that EMG signal includes the motion control policy because EMG signals represent the final motion control signal from the brain. To model this concept, we propose a quantification model of the muscle synergy control based on the synergetic activity between cortico-motoneurons on the cerebral cortex, which output the control signal to multiple muscles. The proposed model is simulated on a musculo-skeletal forward dynamics model that is driven with EMG signal. This quantification is estimated with the EMG refinement process, which estimates the muscle activity with the optimal EMG tuning process based on the synergy control mechanism of multiple muscles in the corticospinal tract. For the discussion, we also introduce some unique results from the proposed model.

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