Wylie Douglas R W, Ogilvie Catherine J, Crowder Nathan A, Barkley Ryan R, Winship Ian R
Department of Psychology, University of Alberta, Edmonton, Alberta, Canada.
Vis Neurosci. 2005 Mar-Apr;22(2):237-47. doi: 10.1017/S0952523805221090.
In birds, the nucleus of the basal optic root (nBOR) of the accessory optic system (AOS) and the pretectal nucleus lentiformis mesencephali (LM) are involved in the analysis of optic flow and the generation of the optokinetic response. In several species, it has been shown that the AOS and pretectum receive input from visual areas of the telencephalon. Previous studies in pigeons using anterograde tracers have shown that both nBOR and LM receive input from the visual Wulst, the putative homolog of mammalian primary visual cortex. In the present study, we used retrograde and anterograde tracing techniques to further characterize these projections in pigeons. After injections of the retrograde tracer cholera toxin subunit B (CTB) into either LM or nBOR, retrograde labeling in the telencephalon was restricted to the hyperpallium apicale (HA) of the Wulst. From the LM injections, retrograde labeling appeared as a discrete band of cells restricted to the lateral edge of HA. From the nBOR injections, the retrograde labeling was more distributed in HA, generally dorsal and dorso-medial to the LM-projecting neurons. In the anterograde experiments, biotinylated dextran amine (BDA) was injected into HA and individual axons were reconstructed to terminal fields in the LM and nBOR. Those fibers projecting to the nBOR also innervated the adjacent ventral tegmental area. However, tracing of BDA-labeled axons revealed no evidence that individual neurons project to both LM and nBOR. In summary, our results suggest that the nBOR and LM receive input from different areas of the Wulst. We discuss how these projections may transmit visual and/or somatosensory information to the nBOR and LM.
在鸟类中，辅助视觉系统（AOS）的基底视根核（nBOR）和中脑顶盖豆状核（LM）参与视流分析和视动反应的产生。在多个物种中，已表明AOS和顶盖前区接收来自端脑视觉区域的输入。先前对鸽子使用顺行示踪剂的研究表明，nBOR和LM均接收来自视觉顶叶隆起（Wulst）的输入，视觉顶叶隆起被认为是哺乳动物初级视觉皮层的同源物。在本研究中，我们使用逆行和顺行示踪技术进一步表征鸽子中的这些投射。在将逆行示踪剂霍乱毒素B亚基（CTB）注射到LM或nBOR中后，端脑中的逆行标记仅限于Wulst的顶叶尖部（HA）。从LM注射后，逆行标记表现为局限于HA外侧边缘的离散细胞带。从nBOR注射后，逆行标记在HA中分布更广，通常在投射到LM的神经元的背侧和背内侧。在顺行实验中，将生物素化葡聚糖胺（BDA）注射到HA中，并重建单个轴突至LM和nBOR中的终末场。那些投射到nBOR的纤维也支配相邻的腹侧被盖区。然而，对BDA标记轴突的追踪未发现单个神经元投射到LM和nBOR两者的证据。总之，我们的结果表明，nBOR和LM接收来自Wulst不同区域的输入。我们讨论了这些投射如何将视觉和/或躯体感觉信息传递到nBOR和LM。
