Uhlrich D J, Manning K A
Department of Anatomy, University of Wisconsin Medical School, Madison 53706, USA.
J Comp Neurol. 1995 Dec 4;363(1):147-59. doi: 10.1002/cne.903630112.
The dorsal lateral geniculate nucleus of the thalamus transmits visual signals from the retina to the cortex. Within the lateral geniculate nucleus, the ascending visual signals are modified by the actions of a number of afferent pathways. One such projection originates in the pretectum and appears to be active in association with oculomotor activity. Much remains unknown about the pretectal-geniculate projection. Our purpose was to examine for the first time individual axon arbors from the pretectum that project to the lateral geniculate nucleus, describing their topography and nuclear and laminar targets. We made injections of the anterograde tracer Phaseolus vulgaris leucoagglutinin into the cat pretectum, targeting the nucleus of the optic tract. Serial 40 microns coronal sections were processed by using immunohistochemistry to reveal labeled axons that were then serially reconstructed using light microscopy. Pretectal-geniculate axons appeared morphologically heterogeneous in terms of swelling size, branching patterns, and laminar target. Most axons innervated the geniculate A laminae. A separate, smaller population innervated the C laminae. All axons exhibited substantially greater spread medial-laterally than rostral-caudally in the lateral geniculate nucleus, displaying a topographical organization for visual field elevation, but not azimuth. Many pretectal axons that projected to the LGN also innervated adjacent structures, including the medial interlaminar nucleus, the perigeniculate nucleus, and/or the pulvinar. These results indicate that the projection from the pretectum to the dorsal lateral geniculate nucleus is heterogeneous, is semitopographical, and may coordinate neural activity in the lateral geniculate nucleus and in neighboring visual thalamic structures in association with oculomotor events.
丘脑的背外侧膝状核将视网膜的视觉信号传递至皮层。在外侧膝状核内，上行视觉信号会受到多种传入通路活动的修饰。其中一种投射起源于顶盖前区，似乎在与眼球运动活动相关时处于活跃状态。关于顶盖前区 - 膝状核投射，仍有许多未知之处。我们的目的是首次检查从顶盖前区投射至外侧膝状核的单个轴突分支，描述它们的拓扑结构以及核和层状靶点。我们将顺行示踪剂菜豆白细胞凝集素注射到猫的顶盖前区，靶向视束核。使用免疫组织化学方法处理40微米厚的连续冠状切片，以显示标记的轴突，然后利用光学显微镜对其进行连续重建。顶盖前区 - 膝状核轴突在肿胀大小、分支模式和层状靶点方面形态各异。大多数轴突支配膝状核的A层。另一较小群体支配C层。在外侧膝状核中，所有轴突在内外侧的分布范围明显大于前后方向，呈现出视野高度的拓扑组织，但没有方位拓扑组织。许多投射至外侧膝状核的顶盖前区轴突还支配相邻结构，包括内侧层间核、膝状周核和/或丘脑枕。这些结果表明，从顶盖前区到背外侧膝状核的投射是异质性的、半拓扑性的，并且可能在眼球运动事件中协调外侧膝状核及相邻视觉丘脑结构中的神经活动。
