Manni E, Bortolami R, Pettorossi V E, Callegari E, Lucchi M L
Arch Ital Biol. 1977 Jan;115(1):20-37.
Several investigations have shown that the vagus nerve and the reticular formation can affect the reflex responses of the masticatory muscles. The present research has been devoted to analyze the mechanism of such modulations of the masseteric reflex in the lamb. Extracellular records of the electrical activity of the mesencephalic trigeminal nucleus (MTN) was carried out in immobilized lambs by means of tungsten microelectrodes. Units were found which responded to lowering the jaw and to stretching the masseter muscle: they were identified as the first-order neurons of the masticatory proprioception on the basis of their electrophysiological properties. Single-shock or repetitive electrical stimulations of the cervical vagus nerve and of the bulbo-pontine reticular formation could affect the unitary discharge of the MTN: different patterns of activation and inhibition of the MTN units were seen; however, the activation was the most prominent effect. The responses did not depend upon the circulatory effects of the vagal stimulation. Thus the conclusion can be reached that the vagus and the reticular substance can modulate the masseteric reflex at level of the perikarya of the afferent pathway. Such a statement is supported also by the presence of synaptic boutons on the soma of the MTN neurons.
多项研究表明，迷走神经和网状结构可影响咀嚼肌的反射反应。本研究致力于分析羔羊咬肌反射这种调节的机制。通过钨微电极在固定的羔羊身上对中脑三叉神经核（MTN）的电活动进行细胞外记录。发现了对下颌下降和咬肌拉伸有反应的神经元：根据其电生理特性，它们被确定为咀嚼本体感觉的一级神经元。对颈迷走神经和延髓 - 脑桥网状结构进行单次电击或重复电刺激可影响MTN的单位放电：观察到MTN神经元有不同的激活和抑制模式；然而，激活是最显著的效应。这些反应并不依赖于迷走神经刺激的循环效应。因此可以得出结论，迷走神经和网状结构可在传入通路的胞体水平调节咬肌反射。MTN神经元胞体上存在突触小体也支持了这一说法。
