Bravo H, Pettigrew J D
J Comp Neurol. 1981 Jul 1;199(3):419-41. doi: 10.1002/cne.901990307.
Using the HRP retrograde transport technique in two different genera of owls (Speotyto and Tyto), we have studied the distribution of neurons projecting to the optic tectum and the visual thalamus. Small injections of HRP were made into these structures from the pial surface after they had been visualized directly by dissection of the overlying bone. In contrast to the findings in mammals, retinal ganglion cells were labeled only in the eye contralateral to the injection site, whether this was in the thalamus or tectum, and the labeled ganglion cells were found on both nasal and temporal sides of the vertical retinal meridian through the fovea. After thalamic injections, labeling was prominent in temporal retina representing the binocular field, temporal to the optic nerve head. Retinothalamic ganglion cells formed roughly concentric lines of isodensity centered on the fovea (Speotyto) or area centralis (Tyto); labeling from thalamic injections involved both large and medium-sized neurons, but did not involve the smallest nor a conspicuous class of very large neurons. Tectal injections led to prominent labeling along the horizontal streak region, with horizontally elongated isodensity contours in both Tyto and Speotyto; retinotectal ganglion cells were heterogeneous and included a group of very large neurons and anther group of small neurons, neither of which was labeled from the thalamus. In the visual Wulst, labeled neurons were confined to the supragranular layers after both tectal and thalamic injections. Corticotectal neurons were found in both ipsilateral and contralateral visual Wulst. They were characterized by large cell bodies and prominent dendrites. Corticotectal neurons were distributed throughout the mediolateral extent of the ipsilateral Wulst and therefore involved both the monocular and binocular representations of the visual field. Corticothalamic neurons, found only in the ipsilateral Wulst, were characterized by smaller cell bodies and fine dendrites. They were confined to the monocular crescent on the extreme medial edge of the World.
利用辣根过氧化物酶（HRP）逆行运输技术，我们在两种不同属的猫头鹰（穴小鸮属和草鸮属）中研究了投射到视顶盖和视觉丘脑的神经元分布。在通过去除覆盖其上的骨骼直接观察到这些结构后，从软膜表面向这些结构中微量注射HRP。与哺乳动物的研究结果相反，无论注射部位是在丘脑还是视顶盖，视网膜神经节细胞仅在注射部位对侧的眼睛中被标记，并且在穿过中央凹的垂直视网膜子午线的鼻侧和颞侧均发现了被标记的神经节细胞。丘脑注射后，在代表双眼视野的视神经乳头颞侧的颞侧视网膜中标记明显。视网膜 - 丘脑神经节细胞大致形成以中央凹（穴小鸮属）或中央区（草鸮属）为中心的同心等密度线；丘脑注射产生的标记涉及大型和中型神经元，但不涉及最小的神经元以及一类明显的非常大的神经元。视顶盖注射导致沿水平条纹区域的明显标记，在草鸮属和穴小鸮属中均有水平拉长的等密度轮廓；视网膜 - 视顶盖神经节细胞是异质的，包括一组非常大的神经元和另一组小神经元，这两组神经元都不会被丘脑注射标记。在视觉顶叶，丘脑和视顶盖注射后，标记的神经元都局限于颗粒上层。在同侧和对侧视觉顶叶均发现了皮质 - 视顶盖神经元。它们的特征是细胞体大且树突明显。皮质 - 视顶盖神经元分布在同侧顶叶的整个内外侧范围，因此涉及视野的单眼和双眼表征。皮质 - 丘脑神经元仅在同侧顶叶中发现，其特征是细胞体较小且树突细小。它们局限于顶叶最内侧边缘的单眼新月区。
