Korp B G, Blanks R H, Torigoe Y
Department of Anatomy and Neurobiology, University of California, Irvine 92717.
Vis Neurosci. 1989;2(3):275-86. doi: 10.1017/s095252380000119x.
The visual pathways from the nucleus of the optic tract (NOT) to the nucleus reticularis tegmenti pontis (NRTP) and prepositus hypoglossi nucleus (ph) were studied following injections of tritiated leucine into the NOT of pigmented rats. The cell bodies of origin of the pretectal-NRTP, NRTP-ph, and pretectal-ph projections were determined using retrograde horseradish peroxidase (HRP) technique. The pretectum projects strongly to the rostral two-thirds of the central and pericentral subdivisions of the NRTP and sends a remarkably smaller projection to the ph. Both are entirely ipsilateral. The fibers destined for the ph travel with the NOT-NRTP bundle, pass through the NRTP, traverse the medial longitudinal fasciculus, and are distributed to the rostral one-half of the ph. The retrograde HRP studies confirm these pathways. The pretectal projections to the NRTP arise from neurons in the rostromedial NOT; those to the ph are located primarily in the rostral NOT although small numbers are found within the anterior, posterior, and olivary pretectal nuclei. Of major importance is the fact that the ph injections retrogradely label neurons within the NRTP and the adjacent paramedian pontine reticular formation. This NRTP-ph projection is entirely bilateral and arises from parts of both subdivisions of the nucleus targeted by NOT afferents. Both the direct NOT-ph and indirect NOT-NRTP-ph connections provide the anatomical basis for the relay of visual (optokinetic) information to the perihypoglossal complex and, presumably, by virtue of reciprocal ph-vestibular nuclear connections, to the vestibular nuclei itself. Such pathways confirm previous physiological studies in rat and, in particular, clarify the contrasting effects of electrolytic lesions of NRTP in rat which completely abolishes optokinetic nystagmus (OKN) (Cazin et al., 1980a) vs kainic acid lesions which produce only minor effects on OKN slow velocity (Hess et al., 1988). Given these differential effects, one concludes that the critical pathway for OKN passes in relation to, but is not significantly relayed by, the neurons of the NRTP or adjacent pontine tegmentum. The present studies suggest that one such fiber system is the NOT-ph bundle. How this relatively small projection compares to other possible fiber of passage systems remains to be determined electrophysiologically.
在给有色大鼠的视束核（NOT）注射氚标记的亮氨酸后，研究了从视束核到脑桥被盖网状核（NRTP）和舌下前置核（ph）的视觉通路。使用逆行辣根过氧化物酶（HRP）技术确定顶盖前 - NRTP、NRTP - ph和顶盖前 - ph投射的起始细胞体。顶盖前区强烈投射到NRTP中央和中央周围亚区的前三分之二，并向ph发出明显较小的投射。两者均完全为同侧投射。去往ph的纤维与NOT - NRTP束一起走行，穿过NRTP，穿过内侧纵束，并分布到ph的前半部分。逆行HRP研究证实了这些通路。顶盖前区向NRTP的投射起源于吻内侧NOT的神经元；向ph的投射主要位于吻侧NOT，尽管在前、后和橄榄顶盖前核内也发现少量投射。最重要的是，ph注射逆行标记NRTP和相邻脑桥旁正中网状结构内的神经元。这种NRTP - ph投射完全是双侧的，起源于NOT传入纤维靶向的核的两个亚区的部分。直接的NOT - ph和间接的NOT - NRTP - ph连接都为视觉（视动）信息传递到舌下周围复合体提供了解剖学基础，并据推测，通过ph - 前庭核的相互连接，传递到前庭核本身。这样的通路证实了先前在大鼠中的生理学研究，特别是阐明了大鼠中NRTP电解损伤完全消除视动性眼球震颤（OKN）（Cazin等人，1980a）与谷氨酸损伤对OKN慢相速度仅产生轻微影响（Hess等人，1988）之间形成对比的效应。鉴于这些不同的效应，可以得出结论，OKN的关键通路与NRTP或相邻脑桥被盖的神经元有关，但不是由它们显著中继的。目前的研究表明，这样一种纤维系统就是NOT - ph束。与其他可能的纤维通路系统相比，这种相对较小的投射如何，仍有待电生理学确定。
