Morphological analysis of the neuronal circuits in the brainstem motor system

我们已经报道了从黑质网状部（SNr）到细胞旁网状形成（RFp）的直接通路，其中已知存在与口面部运动相关的神经元，报道了许多口面部运动核的前运动神经元分布。在本研究中，我们进一步研究了大鼠从SNr到RFp的间接途径。结果表明，红核上丘的近外侧部分和红核的背侧部分，即同侧黑质纤维从信噪比背外侧终止的地方，向对侧RFp发送投射纤维。我们进一步发现，这些黑质轴突对GABA具有免疫反应性，并与顶叶和红叶神经元的体细胞和树突形成对称的突触接触，将轴突发送到RFp。除了从信噪比到RFp的直接途径外，信噪比还通过黑球和黑球到RFp的间接途径对口面部运动施加控制影响。

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.