Zerari-Mailly F, Pinganaud G, Dauvergne C, Buisseret P, Buisseret-Delmas C
Laboratoire de Neuroanatomie Fonctionnelle des Systèmes Sensorimoteurs, 75251 Paris cedex 05, France.
J Comp Neurol. 2001 Jan 1;429(1):80-93. doi: 10.1002/1096-9861(20000101)429:1<80::aid-cne7>3.0.co;2-l.
This study was undertaken to identify premotor neurons in the pontomedullary reticular formation serving as relay neurons between the sensory trigeminal complex and the motor nuclei of the VIIth and XIIth nerves. Trigeminoreticular projections were first investigated after injections of anterogradely transported tracers (biotinylated dextran amine, biocytin) into single subdivisions of the sensory trigeminal complex. The results show that the trigeminoreticular projections were abundant from the pars interpolaris (5i) and caudalis (5c) and moderate from pars oralis (5o) of the spinal trigeminal nucleus. Injections into the 5i and 5c produce dense anterograde labeling (1) in the dorsal medullary reticular field; (2) in the parvocellular reticular field, medially adjacent to the 5i; and (3) more rostral in the region dorsal and lateral to the superior olivary nucleus. Some labeled terminals were also found in the intermediate reticular field, whereas only light anterograde labeling was observed in the gigantocellular and oral pontine reticular formation. The 5o sends fibers and terminals throughout the whole reticular formation, with no clear preferential projections within a particular field. Only light projections originated from the principal nucleus (5P). In a second series of experiments, we examined whether premotor neurons in the reticular formation are afferented by trigeminal fibers. Double labeling was performed by injection of an anterograde tracer in the 5i and 5c and retrograde tracer (gold-horseradish peroxidase complex) into the VII or the XII motor nucleus on the same side. Retrogradely labeled neurons in contact with anterogradely labeled boutons were found throughout the reticular formation with predominance in the parvocellular and intermediate reticular fields. These experiments demonstrate the existence of trigeminal disynaptic influences, via reticular neurons of the pontomedullary reticular formation, in the control of orofacial motor behaviors.
本研究旨在确定脑桥延髓网状结构中的运动前神经元，这些神经元充当感觉三叉神经复合体与第 VII 和第 XII 神经运动核之间的中继神经元。在将顺行性转运示踪剂（生物素化葡聚糖胺、生物胞素）注射到感觉三叉神经复合体的单个亚区后，首先研究了三叉神经网状投射。结果表明，脊髓三叉神经核的极间部（5i）和尾侧部（5c）的三叉神经网状投射丰富，口部（5o）的投射适中。向 5i 和 5c 注射会在以下区域产生密集的顺行标记：（1）延髓背侧网状区；（2）与 5i 内侧相邻的小细胞网状区；（3）更靠前的上橄榄核背侧和外侧区域。在中间网状区也发现了一些标记终末，而在巨细胞和脑桥嘴侧网状结构中仅观察到轻度顺行标记。5o 向整个网状结构发送纤维和终末，在特定区域内没有明显的优先投射。只有来自主核（5P）的轻度投射。在第二系列实验中，我们研究了网状结构中的运动前神经元是否接受三叉神经纤维的传入。通过在 5i 和 5c 注射顺行示踪剂，并在同侧的 VII 或 XII 运动核注射逆行示踪剂（金-辣根过氧化物酶复合物）进行双重标记。在整个网状结构中发现了与顺行标记终扣接触的逆行标记神经元，在小细胞和中间网状区占优势。这些实验证明了通过脑桥延髓网状结构的网状神经元，在口面部运动行为控制中存在三叉神经双突触影响。
