Analysis of the lmbic neural circuits concerned with orofacial movements

我们研究了从中央杏仁核（ACe）到运动三叉神经核和面神经核的控制通路。我们使用生物素化右旋胺和霍乱毒素B亚基联合顺、逆行示踪方法，检测了ACe和直接投射到运动三叉神经或面神经核的运动前神经元的输出纤维的分布。结果表明，ACe纤维与运动前神经元的良好重叠分布主要出现在脑桥和延髓的细胞网状结构中，另外也出现在孤立束核和感觉三叉核中。在细胞网状结构中，常观察到ACe纤维的钮扣样静脉曲张与前运动神经元的体突和树突密切相关。电镜观察显示，ACe纤维主要与前运动神经元的树突形成不对称突触，部分与体细胞形成不对称突触。此外，在轴突-树突突触的活跃区也经常观察到突触致密体。因此，目前的数据表明，ACe可能通过细胞旁网状神经元向下投射到运动三叉神经和面神经核，参与控制情绪的口面部运动。

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.