Morphological analysis of the neuronal circuits in the brainstem motor system

我们已经报道了从黑质(SNR)到小细胞网状结构(RFP)的直接通路，其中已知存在与口面部运动相关的神经元，小细胞网状结构中分布有许多口面部运动核前运动神经元。在本研究中，我们进一步研究了大鼠从SNR到RFP的间接通路，结果表明，在来自SNR背外部的同侧黑质纤维终止处，红核上丘和背部的大部分外侧部分向对侧RFP发出投射纤维。我们进一步证明这些黑质轴突对GABA免疫反应阳性，并与顶盖神经元和红脑神经元的胞体和树突进行对称性突触接触，将轴突发送到RFP。除了SNR到RFP的直接通路外，SNR还被认为通过黑质顶盖球和黑质下球通路到RFP间接地对口面部运动产生控制作用。

We had reported the direct pathway from the substantia nigra pars reticulata (SNr), where the neurons related to orofacial movements had been known to exist, to the parvicellular reticular formation (RFp), where many premotor neurons for the orofacial motor nuclei had been reported to be distributed. In the present study, we further examined the indirect pathways from the SNr to the RFp in the rat.The present results indicated that the lateralmost part of the superior colliculus and dorsal part of the red nucleus, where the ipsilateral nigral fibers from the dorsolateral part of the SNr terminated, sent projection fibers to the contralateral RFp. We further showed that these nigral axons were immunoreactive for GABA and made symmetrical synaptic contacts with somata and dendrites of the tectal and rubral neurons sending their axons to the RFp.In addition to the direct pathway from the SNr to the RFp, the SNr was suggested to exert control influences upon orofacial movements indirectly through the nigrotectobulbar and nigrorubrobulbar pathways to the RFp.