Analysis of the lmbic neural circuits concerned with orofacial movements

我们对杏仁中央核（ACe）到三叉神经运动核和面神经运动核的控制通路进行了研究。应用生物素标记的葡聚糖胺和霍乱毒素B亚单位，对ACe传出纤维和直接投射到三叉神经运动核或面神经运动核的运动前神经元的分布进行了研究，结果表明，ACe纤维和运动前神经元的重叠分布主要在脑桥和延髓的小细胞网状结构内，此外，在孤束核和三叉神经感觉核。在小细胞网状结构内，ACe纤维的终扣样曲张常与运动前神经元的胞体和树突紧密贴壁。电镜观察表明，ACe纤维主要与树突形成不对称性突触，部分与运动前神经元胞体形成不对称性突触。此外，在轴-树突触的活动区还可观察到突触致密体，提示ACe可能通过小细胞网状神经元下行投射到三叉神经运动核和面神经核，参与情绪性口面运动的控制。

We have been studied on the control pathways from the central amygdaloid nucleus (ACe) to the motor trigeminal and facial nuclei. We examined the distribution of efferent fibers from the ACe and that of premotor neurons projecting directly to the motor trigeminal or facial nucleus, using a combined anterograde and retrograde tracing method with biotinylated dextranamine and cholera toxin B subunit.As a result, the good overlapping distribution of the ACe fibers and premotor neurons was found mainly in the parvicellular reticular formation of the pons and medulla oblongata, additionally in the nucleus of the solitary tract and the sensory trigemunal nuclei. Whithin the parvicellular reticular formation, the bouton-like varicosities of the ACe fibers were often observed to be closely apposed to the somata and dendrites of the premotor neurons. In the electron microscopic level, it was revealed that the ACe fibers made asymmetrical synapses predominantly with dendrites and partly with somata of the premotor neurons. Furthermore, synaptic dense bodies were often observed in the active zone of the axo-dendritic synapses.Thus, the present data suggest that the ACe may take part in the control of emotional orofacial movements through its descending projections to the motor trigeminal and facial nuclei via the parvicellular reticular neurons.