Northcutt R G, Butler A B
Brain Res. 1980 May 26;190(2):333-46. doi: 10.1016/0006-8993(80)90278-4.
Efferent projections of the optic tectum were studied with the anterograde degeneration method in the longnose gar. Ascending projections were found bilaterally to 3 pretectal nuclei -- the superficial pretectal nucleus, nucleus pretectalis centralis and nucleus pretectalis profundus -- and to a number of targets which lie further rostrally -- the central posterior nucleus, dorsal posterior nucleus, accessory optic nucleus, nucleus ventralis lateralis, nucleus of the ventral optic tract, rostral part of the preglomerular complex, suprachiasmatic nucleus, anterior thalamic nucleus, nucleus ventralis medialis, nucleus intermedius, nucleus prethalamicus and rostral entopeduncular nucleus. Projections of the tectum reach the contralateral side via the supraoptic decussation and are less dense contralaterally than ipsilaterally. Descending projections resulting from tectal lesions include: (1) a tectal commissural pathway to the core of the torus longitudinalis bilaterally and the contralateral tectum and torus semicircularis; and (2) a pathway leaving the tectum laterally from which fibers terminate in the ipsilateral torus semicircularis, an area lateral to the nucleus of the medial longitudinal fasciculus, lateral tegmental nucleus, nucleus latealis valvulae, nucleus isthmi and the reticular formation. A component of this bundle decussates at the level of the lateral tegmental nucleus to project to the contralateral reticular formation. On the basis of comparisons of these findings with the pattern of retinal projections in gars and other data, it is argued that the nuclei previously called the lateral geniculate and rotundus in fish are not the homologues of the nuclei of those names in land vertebrates but are rather pretectal cell groups. The overall organization of both retinal and tectal projections in gars is strikingly similar to that in land vertebrates; at present, the best candidate for a rotundal homologue is the dorsal posterior nucleus.
采用顺行变性法，对长吻雀鳝视顶盖的传出投射进行了研究。发现其双侧上行投射至3个顶盖前核，即浅顶盖前核、顶盖前中央核和顶盖前深核，以及一些更靠前的靶点，包括中央后核、背侧后核、副视核、外侧腹核、视束腹侧核、前肾小球复合体的前部、视交叉上核、丘脑前核、内侧腹核、中间核、丘脑前核和前内侧缰核。视顶盖的投射通过视交叉上连合到达对侧，对侧的投射密度低于同侧。视顶盖损伤导致的下行投射包括：（1）一条视顶盖连合通路，双侧通向纵纹隆起的核心以及对侧视顶盖和半规隆起；（2）一条从视顶盖外侧发出的通路，其纤维终止于同侧半规隆起、内侧纵束核外侧的一个区域、外侧被盖核、瓣膜外侧核、峡核和网状结构。该束的一部分在外侧被盖核水平交叉，投射至对侧网状结构。基于将这些发现与雀鳝视网膜投射模式及其他数据进行比较，有人认为鱼类中先前被称为外侧膝状体和圆核的核团并非陆地脊椎动物中同名核团的同源物，而是顶盖前细胞群。雀鳝视网膜和视顶盖投射的整体组织与陆地脊椎动物的极为相似；目前，圆核同源物的最佳候选者是背侧后核。
