Yang J, Türker K S
Oral Neurophysiology Laboratory, Department of Physiology, The University of Adelaide, SA 5005, Adelaide, Australia.
Arch Oral Biol. 2001 Nov;46(11):989-96. doi: 10.1016/s0003-9969(01)00075-9.
The distribution of the synaptic input from the periodontal mechanoreceptors onto the motoneurons of the human masseter is studied. Periodontal mechanoreceptors were activated using slowly rising force profiles of 2.5 N, which are known to induce predominantly excitatory reflex responses in the surface electromyogram (EMG) of the masseter. The reflex responses of single motor units (SMUs) were recorded to quantify the distribution of the periodontal input onto the masseter motoneurons. The relative sizes of motoneurons were estimated by comparing the peak-to-peak amplitude of the MacroRep (i.e. the representation of the SMU in the Macro EMG record). It was found that the larger SMUs had more excitatory and less inhibitory reflex responses than those of smaller size. This study demonstrates that the inputs from the periodontal mechanoreceptors, activated by slowly rising force profiles, are not distributed equally to the masseteric motoneurons. This may cause recruitment of motoneurons contrary to the size principle under some circumstances.
研究了牙周机械感受器向人类咬肌运动神经元的突触输入分布。使用2.5N的缓慢上升力曲线激活牙周机械感受器，已知该力曲线在咬肌表面肌电图（EMG）中主要诱发兴奋性反射反应。记录单个运动单位（SMU）的反射反应，以量化牙周输入在咬肌运动神经元上的分布。通过比较MacroRep的峰峰值幅度（即Macro EMG记录中SMU的表现）来估计运动神经元的相对大小。结果发现，较大的SMU比较小的SMU具有更多的兴奋性反射反应和更少的抑制性反射反应。这项研究表明，由缓慢上升力曲线激活的牙周机械感受器的输入并非均匀地分布到咬肌运动神经元上。在某些情况下，这可能导致与大小原则相反的运动神经元募集。
