Center-surround organization in bipolar cells: Symmetry for opposing contrasts
Center-surround organization in bipolar cells: Symmetry for opposing contrasts
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DOI：
10.1017/s0952523803201012
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发表时间：
2003-01-01
影响因子：
1.9
通讯作者：
Burkhardt, DA
中科院分区：
文献类型：
--
作者：
Fahey, PK;Burkhardt, DA
细胞内记录获得73锥驱动的双极细胞在光适应的虎蝾螈（Ambystoma tigrinum）的视网膜。作为对比度大小的函数，分析了中心光斑和最佳空间尺寸的同心环对负对比度和正对比度闪光的响应。对于去极化和超极化双极细胞，人们发现，显着相似的反应，观察到的中心和周围的反应时，进行比较，作出相同的反应极性的反应，因此，相反的对比极性的反应。因此，在许多双极细胞中，空间信息和对比极性似乎是相当强烈的混淆。通常，中心和周围的对比度/响应曲线的形式近似于彼此的镜像。当对相同响应极性的响应进行比较时，中心和周围的对比度增益和C-50（半最大响应所需的对比度）在数量上相似。双极细胞周围的平均对比度增益比水平细胞的平均对比度增益高3-5倍。对比度/潜伏期测量和闪光点和环带之间的相互作用表明，周围的反应延迟20-80毫秒相对于接收场中心。视锥细胞没有显示出中心-周围拮抗的证据，而对于双极细胞，周围的平均强度范围为中心的50%至155%，这取决于测试和反应极性。APB（100 μ M）对去极化双极细胞的影响的实验结果表明，反馈途径（水平细胞锥）和前馈途径（水平细胞双极细胞）的相对贡献的双极环绕在整个双极细胞群体的分布方式不同。
Intracellular recordings were obtained from 73 cone-driven bipolar cells in the light-adapted retina of the tiger salamander (Ambystoma tigrinum). Responses to flashes of negative and positive contrast for centered spots and concentric annuli of optimum spatial dimensions were analyzed as a function of contrast magnitude. For both depolarizing and hyperpolarizing bipolar cells, it was found that remarkably similar responses were observed for the center and surround when comparisons were made between responses of the same response polarity and thus, responses to opposite contrast polarity. Thus, spatial information and contrast polarity appear to be rather strongly confounded in many bipolar cells. As a rule, the form of the contrast/response curves for center and surround approximated mirror images of each other. Contrast gain and C-50 (the contrast required for half-maximal response) were quantitatively similar for center and surround when comparisons were made for responses of the same response polarity. The average contrast gain of the bipolar cell surround was 3-5 times higher than that measured for horizontal cells. Contrast/latency measurements and interactions between flashed spots and annuli showed that the surround response is delayed by 20-80 ms with respect to that of the receptive-field center. Cones showed no evidence for center-surround antagonism while for bipolar cells, the average strength of the surround ranged from about 50% to 155% of the center, depending on the test and response polarity. The results of experiments on the effects of APB (100 muM) on depolarizing bipolar cells suggest that the relative contribution of the feedback pathway (horizontal cell to cones) and the feedforward pathway (horizontal cell to bipolar cell) to the bipolar surround varies in a distributed manner across the bipolar cell population.