van der Glas H W, de Laat A, Carels C, van Steenberghe D
Department of Periodontology, School of Dentistry, Oral Pathology and Maxillofacial Surgery, Catholic University of Leuven, Belgium.
Brain Res. 1988 Mar 22;444(2):284-94. doi: 10.1016/0006-8993(88)90937-7.
Post-stimulus electromyogram (EMG) complexes (PSECs) were studied in the full-wave rectified and averaged EMGs of the masseter muscles in 15 subjects, who clenched at a controlled level. The PSECs, a series of downward- and upward-going waves reflecting inhibitory and excitatory influences upon the masseteric motoneurones, were elicited by mechanical stimulation of a tooth. The stimuli selectively activated mechanoreceptors in the periodontium and, by bone-conduction, acoustic receptors. Application of acoustic masking during the periods of stimulation revealed a series of inhibitory and excitatory acoustic influences in the PSEC, which were absent after local electrical stimulation of receptors in the periodontium or their afferents. By applying local anaesthesia to the periodontium of a mechanically stimulated tooth, the durations of the acoustic influences were on the average reduced by 76%. In subjects whose PSECs consistently included a second inhibitory period, the duration of the acoustic influences with respect to that of the PSEC (30%) was larger than otherwise (13%), suggesting a central gating of periodontal pathways which can block both periodontal and acoustic influences. The acoustic influences, of which the appearance in the PSEC largely depends upon activated periodontal pathways, represent a new finding of audio-motor reflexes.
在15名以可控力度紧咬牙的受试者的咬肌全波整流平均肌电图中，对刺激后肌电图复合体（PSECs）进行了研究。PSECs是一系列反映对咬肌运动神经元抑制性和兴奋性影响的上下行波，由牙齿的机械刺激引发。这些刺激选择性地激活了牙周膜中的机械感受器，并通过骨传导激活了听觉感受器。在刺激期间施加声掩蔽，揭示了PSEC中一系列抑制性和兴奋性听觉影响，而在局部电刺激牙周膜中的感受器或其传入神经后，这些影响则不存在。通过对机械刺激牙齿的牙周膜施加局部麻醉，听觉影响的持续时间平均减少了76%。在PSECs始终包含第二个抑制期的受试者中，听觉影响相对于PSEC的持续时间（30%）比其他情况（13%）更大，这表明牙周途径存在中枢性门控，可阻断牙周和听觉影响。听觉影响在很大程度上取决于激活的牙周途径而在PSEC中出现，这代表了一种新的听觉运动反射发现。
