Gruberg E R, Udin S B
J Comp Neurol. 1978 Jun 1;179(3):487-500. doi: 10.1002/cne.901790303.
The connections between the nucleus isthmi and the tectum in the frog have been determined by several anatomical techniques: iontophoresis of horseradish peroxidase into the tectum, iontophoresis of 3H-porline into the nucleus isthmi and the tectum, and Fink-Heimer degeneration staining after lesions of the nucleus isthmi. The results show that the nucleus isthmi projects bilaterally to the tectal lobes. The ipsilateral isthmio-tectal fibers are distributed in the superficial layers of the tectum, coincident with the retionotectal terminals. The contralateral isthmio-tectal fibers travel anteriorly adjacent to the lateral optic tract and cross the midline in the supraoptic ventral decussation, where they turn dorsally and caudally; upon reaching the tectum, the fibers end in two discrete layers, layers 8 and A of Potter. The tectum projects to the ipsilateral nucleus isthmi and there is a reciprocal topographic relationship between the two structures. Thus, a retino-tecto-isthmio-tectal route exists which may contribute to the indirect ipsilateral retinotectal projection which is observed electrophysiologically. The connections between the nucleus isthmi and the tectum in the frog are strinkingly similar to the connections between the parabigeminal nucleus and the superior colliculus of mammals.
将辣根过氧化物酶离子导入顶盖、将³H-脯氨酸离子导入峡核和顶盖，以及在峡核损伤后进行芬克-海默变性染色。结果表明，峡核双侧投射到顶盖叶。同侧峡核-顶盖纤维分布在顶盖的浅层，与视网膜-顶盖终末重合。对侧峡核-顶盖纤维向前走行，与外侧视束相邻，并在视上腹中交叉处穿过中线，在此处它们转向背侧和尾侧；到达顶盖后，纤维终止于两个离散的层，即波特的第8层和A层。顶盖投射到同侧峡核，并且这两个结构之间存在相互的拓扑关系。因此，存在一条视网膜-顶盖-峡核-顶盖通路，这可能有助于电生理学上观察到的间接同侧视网膜-顶盖投射。青蛙峡核与顶盖之间的连接与哺乳动物的副视核与上丘之间的连接惊人地相似。
