V1 to V2 Projections in Normal Vision and Amblyopia

在灵长类动物中，视觉信息从初级视觉区（V1）传递到第二视觉区（V2），然后再分配到高级皮质区。准确描述连接v1和V2的投影对于理解大脑如何解读视觉图像至关重要。先前的研究表明，V2被分为三个区室，分别是浅条纹、细条纹和粗条纹，由细胞色素氧化酶（CO）的代谢酶含量决定。我们的主要目标是描述从V1到每个V2条纹室的解剖投影。在具体目标#1中，我们将在正常猕猴V2的单个CO条纹中注射逆行示踪剂。所得到的V1中标记细胞的图案将与接受注射的V2条带相关联。我们的初步数据表明，与之前的报告相反，层4B和interblobs都突出为粗条纹和淡条纹。在Specific Aim #2中，我们将配对注射两种不同的示踪剂到相邻的粗条纹和淡条纹中，以确定4B层和interblobs中不同的细胞亚群是否投射到这些V2区室。在Specific Aim #3中，我们将在V1中注射[3H]脯氨酸，将V2中的出射投影斑块与CO染色模式相关联。在special Ai/s #4中，我们将研究早期单眼剥夺饲养的动物的V1->V2投影。这些实验将提高我们对弱视机制的认识，弱视是影响2%美国人视力丧失的重要原因。我们假设，选择性的V1->V2投射的丧失，从眼优势柱服务于被剥夺的眼睛有助于弱视的视力丧失。

In primates, visual information passes from the primary visual area (V1) to the second visual area (V2) before distribution to higher cortical areas. An accurate description of the projections linking V 1 and V2 is crucial for understanding how the brain deciphers visual images. Prior studies have shown that V2 is partitioned into three compartments, known as pale, thin, and thick stripes, defined by their content of a metabolic enzyme called cytochrome oxidase (CO). Our principal goal is to describe the anatomical projections from V1 to each V2 stripe compartment. In Specific Aim #1 we will make injections of a retrograde tracer into single CO stripes in V2 of normal macaques. The resulting pattern of labeled cells in V1 will be correlated with the V2 stripe that received the injection. Our preliminary data indicate that, contrary to a previous report, layer 4B and interblobs both project to thick stripes and pale stripes. In Specific Aim #2 we will make paired injections of two different tracers into adjacent thick stripes and pale stripes to determine if different subpopulations of cells in layer 4B and interblobs project to these V2 compartments. In Specific Aim #3 we will make injections of [3H]proline into V1 to correlate patches of efferent projections with CO staining patterns in V2. In Specific Ai/s #4 we will examine the V1->V2 projections in animals raised with early monocular deprivation. These experiments will advance our knowledge of the mechanisms underlying amblyopia, an important cause of visual loss that affects 2% of the American population. We hypothesize that a selective loss of V1->V2 projections emanating from the ocular dominance columns serving the deprived eye contributes to the loss of vision in amblyopia.