Anatomical investigation on the visual input to the regions related to the optokinetic responses.

NOT和AON都接受视网膜的直接输入，对视动反应(OKR)起着调节作用。利用WGA-HRP作为顺行示踪剂，结合GABA免疫组织化学方法，对猫视网膜和纹外外侧视皮质向NOT和AON的传出进行了超微结构研究。在NOT和AON中，视网膜终末(RT)都很多。这些终末含有苍白的线粒体和圆形的突触小泡。NOT的RTS较大，与GABA阴性的常规树突和含有囊泡的GABA阳性树突形成非对称性突触接触，参与肾小球；AON的RTS较小，主要与常规树突非对称接触。AON未见典型的视网膜小球。大脑皮层…的形态或突触组织似乎没有差别。在NOT和怡安之间有更多的L终端(CT)。CTs总是很小，并且与GABA阴性的常规树枝晶不对称接触。这些结果表明，RTS和CTS在突触结构上存在形态上的差异，反映了它们在加工视觉信息方面的质的差异。此外，在NOT和AON中，RTS在形态上是相同的，反映了它们在视觉处理中的独特作用。然后，我们使用示踪剂(小麦胚芽凝集素标记的辣根过氧化物酶、WGA-HRP和霍乱毒素B亚单位CTB)研究了大鼠视网膜和视觉皮质区域(17、18a和18b区)到NOT的投射，以阐明OKR的这两种不同功能输入是如何组织的。CTB注入玻璃体后，对侧眼几乎只出现顺行标记。在超微结构上，视网膜轴突终末较小(直径可达0.7mGbA)，含有圆形突触小泡和苍白的线粒体，与GABA阳性和阴性的NOT神经元均有不对称的突触接触。视皮层17区和17区与18a区之间或17区与18b区之间的过渡区将轴突投射到同侧NOT。在超微结构上，皮质轴突终末较小(直径可达0.5GbA/μm)，内含圆形突触小泡，仅与GABA阴性的NOT神经元发生非对称性突触接触。通过光镜和电子显微镜观察，皮质-NOT和Retino-NOT投射模式有相当大的重叠：GABA阴性(可能不投射)神经元同时接受皮质和视网膜终末的输入。根据这些结果，似乎有理由假设，来自色素沉着大鼠的视觉皮质区域的输入与来自视网膜的输入在控制OKR方面是协同的。较少

The NOT and AON, which both receive direct retinal inputs, perform a regulatory function on optokinetic responses (OKR). The geniculostriate pathway influences on this regulation, apparently via extrastriate areas involved in motion processing.Retina and extrastriate lateral suprasylvian visual cortical efferents to NOT and AON have been studied ultrastructually in cats using WGA-HRP as anterograde tracer in combination with GABA immunohistochemistry. Retinal terminals (RTs) are numerous in both NOT and AON. These terminals contain pale mitochondria and round synaptic vesicles. RTs in NOT are often large and make asymmetrical synaptic contact with GABA-negative conventional dendrites and vesicle-containing GABA-positive dendrites which participate in glomeruli, while RTs in AON are small and make asymmetrical contacts mainly with conventional dendrites. No typical retinal glomeruli are found in AON. There appear to be no differences in morphology or synaptic organization of the cortica … More l terminals (CTs) between NOT and AON. CTs always are small, and make asymmetrical contact with GABA-negative conventional dendrites. The present results indicate that RTs and CTs differ morphologically in synaptic structure, reflecting their qualitative difference in processing visual information. Furthermore, RTs are morphologically identical in NOT and AON, reflecting their unique role in visual processing.Then, we have examined the projections from the retina and visual cortical areas (areas 17, 18a and 18b) to NOT in rats using tracers (wheat germ agglutinin-conjugated horseradish peroxidase, WGA-HRP and cholera toxin B subunit, CTB) in order to clarify how these two different functional inputs to OKR are organized. CTB injection into the vitreous body resulted in anterograde label almost exclusively in the contralateral NOT. Ultrastructually, the size of the retinal axon terminals was small (up to 0.7 μm in diameter), contained round synaptic vesicles and pale mitochondria, and made asymmetrical synaptic contacts with both GABA-positive and GABA-negative NOT neurons. Visual cortical area 17 and the transitional area between area 17 and 18a, or between area 17 and 18b projected their axons to the ipsilateral NOT. Ultrastructually, the size of the cortical axon terminals was small (up to 0.5 μm in diameter), contained round synaptic vesicles, and made asymmetrical synaptic contacts only with GABA-negative NOT neurons. With light and electron microscopical observation, there was a considerable overlap in the cortico-NOT and retino-NOT projection pattern : GABA-negative (presumably NOT projection) neurons simultaneously receive input from both cortical and retinal terminals. From these results, it seems reasonable to postulate that inputs from visual cortical areas in the pigmented rat cooperate with those from the retina in controlling OKR. Less