Shmuel Amir, Korman Maria, Sterkin Anna, Harel Michal, Ullman Shimon, Malach Rafael, Grinvald Amiram
Department of Neurobiology, The Weizmann Institute of Science, 76100 Rehovot, Israel.
J Neurosci. 2005 Feb 23;25(8):2117-31. doi: 10.1523/JNEUROSCI.4137-04.2005.
Cortical maps and feedback connections are ubiquitous features of the visual cerebral cortex. The role of the feedback connections, however, is unclear. This study was aimed at revealing possible organizational relationships between the feedback projections from area V2 and the functional maps of orientation and retinotopy in area V1. Optical imaging of intrinsic signals was combined with cytochrome oxidase histochemistry and connectional anatomy in owl monkeys. Tracer injections were administered at orientation-selective domains in regions of pale and thick cytochrome oxidase stripes adjacent to the border between these stripes. The feedback projections from V2 were found to be more diffuse than the intrinsic horizontal connections within V1, but they nevertheless demonstrated clustering. The clusters of feedback axons projected preferentially to interblob cytochrome oxidase regions. The distribution of preferred orientations of the recipient domains in V1 was broad but appeared biased toward values similar to the preferred orientation of the projecting cells in V2. The global spatial distribution of the feedback projections in V1 was anisotropic. The major axis of anisotropy was systematically parallel to a retinotopic axis in V1 corresponding to the preferred orientation of the cells of origin in V2. We conclude that the feedback connections from V2 to V1 might play a role in enhancing the response in V1 to collinear contour elements.
皮质图谱和反馈连接是视觉大脑皮层的普遍特征。然而，反馈连接的作用尚不清楚。本研究旨在揭示V2区的反馈投射与V1区的方向功能图谱和视网膜拓扑之间可能存在的组织关系。将内在信号的光学成像与猫头鹰猴的细胞色素氧化酶组织化学和连接解剖学相结合。在与这些条纹边界相邻的淡色和深色细胞色素氧化酶条纹区域的方向选择性区域进行示踪剂注射。发现来自V2的反馈投射比V1内的内在水平连接更分散，但它们仍表现出聚集。反馈轴突簇优先投射到细胞色素氧化酶的斑间区域。V1中接受域的偏好方向分布广泛，但似乎偏向于与V2中投射细胞的偏好方向相似的值。V1中反馈投射的全局空间分布是各向异性的。各向异性的主轴系统地平行于V1中与V2中起源细胞的偏好方向相对应的视网膜拓扑轴。我们得出结论，从V2到V1的反馈连接可能在增强V1对共线轮廓元素的反应中起作用。
