Komiyama Osamu, Wang Kelun, Svensson Peter, Arendt-Nielsen Lars, De Laat Antoon
Department of Oral and Maxillofacial Surgery, School of Dentistry, Oral Pathology and Maxillo-Facial Surgery, Catholic University of Leuven, Kapucijnenvoer 7, B-3000 Leuven, Belgium.
Arch Oral Biol. 2005 Dec;50(12):994-1004. doi: 10.1016/j.archoralbio.2005.04.001. Epub 2005 May 31.
The present study documented quantitative changes in the duration and the depth of the exteroceptive suppression (ES) period in the masseteric electromyogram (EMG) using stimulus-response (SR) curves. From six males and six females (20-41 years), the surface masseteric EMG was recorded bilaterally. Visual feedback from the left masseter muscle (MM) allowed a constant clenching level of 30% or 50% maximal voluntary contraction (MVC). Automatic triggering of the stimulus to the left mental nerve occurred when the background EMG remained constant. Eight to twelve stimulus intensities (range, 0-40 mA) were determined based on the subjects' sensory threshold (T). The late ES (ES2) occurred consistently and could be analyzed using SR curves. ES2 in the right MM appeared at 7.3+/-3.1T at 30% MVC, while it was significantly decreased to 5.2+/-2.2T at 50% MVC (P<0.05). The depth of ES2 suppression in the left MM was 69.7+/-5.7% at 30% MVC, and this increased significantly to 76.6+/-5.5% at 50% MVC (P<0.05). In addition, the depth of ES2 suppression in the left MM was significantly higher than that in the right MM at 50% MVC (70.0+/-7.4%, P<0.05). Consequently, it was confirmed that both the appearance and depth of ES may be affected by the level of background EMG. More importantly, the use of multiple stimulation intensities allowed development of reliable SR curves. These SR curves may be used to determine inter-individual differences in ES.
本研究使用刺激-反应（SR）曲线记录了咬肌肌电图（EMG）中外感受性抑制（ES）期的持续时间和深度的定量变化。对6名男性和6名女性（20 - 41岁）双侧记录表面咬肌EMG。来自左侧咬肌（MM）的视觉反馈使咬肌保持在最大自主收缩（MVC）的30%或50%的恒定收缩水平。当背景EMG保持恒定时，自动触发对左侧颏神经的刺激。根据受试者的感觉阈值（T）确定8至12种刺激强度（范围为0 - 40 mA）。晚期ES（ES2）持续出现，可使用SR曲线进行分析。右侧MM的ES2在30%MVC时出现在7.3±3.1T，而在50%MVC时显著降至5.2±2.2T（P<0.05）。左侧MM在30%MVC时ES2抑制深度为69.7±5.7%，在50%MVC时显著增加至76.6±5.5%（P<0.05）。此外，在50%MVC时，左侧MM的ES2抑制深度显著高于右侧MM（70.0±7.4%，P<0.05）。因此，证实了ES的出现和深度可能受背景EMG水平的影响。更重要的是，使用多种刺激强度可绘制出可靠的SR曲线。这些SR曲线可用于确定ES的个体间差异。
