Parallel pathways in visual cortex: functional connectivity of output pathways fr

描述(申请人提供)：理解大脑皮层神经回路的组织原理对于理解它们的计算功能是必要的。这一原理催生了“连接学”的新领域，致力于在不同的尺度上生成大脑的接线图或大脑的不同部分。在灵长类动物的视觉皮质中，V1和V2区将它们从视网膜接收的信息分发到几乎所有的高级区域，分别将这些信息分类到空间和物体视觉的背侧和腹侧加工流中。这个应用程序的目的是揭示V1和V2的解剖和功能连接的规则 为了了解这些区域如何将视网膜信号提炼和重组为视觉处理流，以及这些路径如何有助于在较高区域创建复杂的感受场(RF)属性，我们需要对输出路径进行研究。从V1到V2的平行通路投射出明显的细胞色素氧化酶条纹(粗、细和淡)。在上一次拨款期间 期间，我们发现了V1和V2之间的4条分离通路。我们还发现V1通路的特殊功能组织与粗纹和淡纹有关，这可能是V2RF对倾斜和弯曲轮廓的反应的基础。这项建议建立在这些发现的基础上。目标1的目的是通过确定单个V1输出细胞在V1和V2方位图上的轴突和树突布局，了解单个V1细胞如何有助于产生V2 RFs。我们将首次在介观尺度上提供投射到特定V2条纹的V1细胞的全面解剖学描述，包括V1内和V2内 确定的细胞类型的轴突分支，以及它们在V1和V2内的功能组织。这些信息将提供对前馈和V2内机制在V2RF产生中的作用的洞察，以及V1内和V1到V2电路对轮廓处理的贡献。然后，我们将研究V2下游4条通路的解剖和功能分离是否保持或消失。AIM2的目标是确定两种V2苍白条纹类型的面积投影，我们最近证明这两种类型是不同的间隔。这项研究将确定每个苍白条纹对背侧和腹侧加工流的贡献。V2和V4包含视觉刺激方向和颜色的分离表示。Aim3的目标是确定V2和V4之间的连接是否发生在具有相似特征表示的区域之间，或者是否在V4中发生跨流收敛。这项研究还将深入了解前馈机制与区域内机制在V4RF和特征图生成中的作用。拟议的研究具有重要意义，因为它将揭示V1和V2输出的解剖和功能连接原理 这些通路将作为假说驱动和解剖学限制的功能研究的基础。这项拟议的研究具有创新性，因为它结合了功能成像和单轴突的高分辨率标记，使用了单轴突标记和重建的新方法。

DESCRIPTION (provided by applicant): Understanding organizing principles for neural circuits in the cortex is necessary to understand their computational function. This principle has informed the new field of "connectomics", devoted to generating wiring diagrams of the brain, or subsections of it, at different scales. In the primate visual cortex, areas V1 and V2 distribute information they receive from the retina to virtually all higher areas, sorting this information ino dorsal and ventral processing streams for spatial and object vision, respectively. The objective of this application is to uncover the rules of anatomical and functional connectivity for V1 and V2 output pathways, in order to understand how these areas may refine and re-organize retinal signals into visual processing streams, and how these pathways contribute to creating the complex receptive field (RF) properties of neurons in higher areas. Parallel pathways from V1 to V2 project to distinct cytochrome-oxidase stripes (thick, thin and pale). During the previous grant period, we discovered 4 segregated pathways between V1 & V2. We also discovered specialized functional organizations of V1 pathways related to thick and pale stripes that may underlie the responses of V2 RFs to angled and curved contours. This proposal builds upon these findings. The goal of Aim 1 is to understand how single V1 cells contribute to generating V2 RFs, by determining the axonal and dendritic layout of single V1 output cells over the V1 and V2 orientation maps. We will provide the fist comprehensive anatomical description at mesoscopic scale of V1 cells projecting to specific V2 stripes, including the intra-V1 and intra-V2 axonal arborizations of identified cell types, and their functional organization within both V1 & V2. This information will provide insights into the roles of feedforward vs. intra-V2 mechanisms in the generation of V2 RFs, and on the contribution of intra-V1 and V1-to-V2 circuits to the processing of contours. We will then investigate whether anatomical and functional segregation of the 4 pathways is maintained or lost downstream of V2. The goal of Aim2 is to determine the areal projections of the two V2 pale stripe types, which we have recently demonstrated to be distinct compartments. This study will determine each pale stripe contribution to the dorsal and ventral processing streams. V2 and V4 contain segregated representations for visual stimulus orientation and color. The goal of Aim3 is to determine whether connections between V2 & V4 occur between regions of similar featural representation, or whether cross-stream convergence occurs in V4. This study will also provide insights into the roles of feedforward vs. intra-areal mechanisms in the generation of V4 RFs and featural maps. The proposed research is significant because it will reveal anatomical and functional wiring principles for V1 and V2 output pathways that will serve as a foundation for hypothesis-driven and anatomically-constrained studies of their function. The proposed research is innovative because it combines functional imaging with high-resolution labeling of single axons, using novel methods for single axon labeling and reconstruction.