Morphological experiments of the control of jaw movements in the forebrain

我们已经指出，黑质网状部（SNr）的背外侧部分，这是基底节的主要输出核之一，在控制颌骨运动中起着重要的作用。外侧无颗粒皮质（AGi）的吻腹侧部分和纹状体的腹外侧部分被认为是控制口面运动的区域，在本研究中，我们采用顺行和逆行相结合的追踪技术，研究了从SNr背外侧部到AGl吻腹侧部和纹状体腹外侧部的可能通路，这些通路由丘脑中继。结果表明，SNr的背外侧部发出投射纤维至丘脑束旁核（PE）的腹外侧部。其次，在PF的腹外侧部，黑质纤维与投射到AGl的吻腹侧部或纹状体腹外侧部的PF神经元重叠分布，这部分PF不仅含有投射到AGl的吻腹侧部的神经元，而且含有许多投射到纹状体腹外侧部的神经元。黑质轴突终末与投射到AG 1或纹状体的PF神经元的索马体和树突形成对称性突触接触。因此，本研究揭示的SNr-PF-AG 1和SNr-PF-纹状体通路可能参与口面运动功能的控制机制。

We have already indicated that the dorsolateral part of the substabtia nigra pars reticulata (SNr), which is one of the major output nuclei of the basal ganglia, plays an important role in the control of jaw movement. The rostroventral part of the lateral agranular cortex (AGi) and the ventrolateral part of the striatum have been known as the area involved in the control of orofacial movement, In the present study, we examined the possible pathways from the dorsolateral part of the SNr to the rostroventral part of the AGl and the ventrolateral part of the striatum relayed by the thalamus using a combined anterograde and retrograde tracing technique.We first showed that the dorsolateral part of the SNr sent projection fibers to the ventrolateral part of the parafascicular thalamic nucleus (PE). Secondly, we indicated the overlapping distributions of the nigral fibers and the PF neurons projecting to the rostroventral part of the AGl or to the ventrolateral part of the striatum in the ventrolateral part of the PF.This part of the PF contained not only some neurons projecting to the rostroventral part of the AGl, but also many neurons projecting to the ventrolateral part of the striatum. The nigral axon terminals made symmetrical synaptic contacts with the soma and dendrites of the PF neurons projecting to the AGl or to the striatum. Thus, the SNr-PF-AGl and SNr-PF-striatal pathways revealed by the present study may be involved in the control mechanism of orofacial motor functions.