A COMPARISON OF RECEPTIVE-FIELD AND TRACER COUPLING SIZE OF HORIZONTAL CELLS IN THE RABBIT RETINA
A COMPARISON OF RECEPTIVE-FIELD AND TRACER COUPLING SIZE OF HORIZONTAL CELLS IN THE RABBIT RETINA
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DOI：
10.1017/s0952523800009524
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发表时间：
1995-09-01
影响因子：
1.9
通讯作者：
PERSKY, SE
中科院分区：
文献类型：
--
作者：
BLOOMFIELD, SA;XIN, DY;PERSKY, SE
视网膜水平细胞的大感受野被认为反映了通过缝隙连接的广泛的电耦合。最近显示，生物素标记的示踪剂，生物胞素和神经生物素，提供了许多类型的视网膜神经元之间的耦合，包括水平细胞的显着图像。此外，这些水平细胞之间的示踪剂耦合的演示与它们的感受野的大小相媲美，这表明示踪剂耦合的模式可以提供电耦合程度的一些指数。我们研究了这个问题，通过比较暗适应水平细胞的感受野和示踪剂耦合的大小记录在灌流，离体视网膜眼杯的兔子。边缘到边缘的感受野和空间常数（λ）都是使用长而窄的光缝穿过视网膜表面来计算的。随后通过离子电渗注射神经生物素标记细胞。无轴突的A型水平细胞在大于1000个覆盖距离平均约2 mm的组中显示出广泛的同源示踪剂偶联。显示了跨越约400 μ m的约100个细胞的组中的体细胞末端的同源偶联，以及仅覆盖约275亩。此外，我们观察到一个显着的，线性关系的大小之间的感受野的每一个水平的细胞末梢和它们的示踪剂耦合的大小。我们的研究结果表明，示踪剂耦合的程度提供了一个强大的，线性指数的电流的大小，来自感受场的措施，跨组耦合的水平细胞。因此，这些数据提供了第一个直接的证据表明，水平细胞的感受野大小与它们通过间隙连接的耦合程度有关。
The large receptive fields of retinal horizontal cells are thought to reflect extensive electrical coupling via gap junctions. It was shown recently that the biotinylated tracers, biocytin and Neurobiotin, provide remarkable images of coupling between many types of retinal neuron, including horizontal cells. Further, these demonstrations of tracer coupling between horizontal cells rivaled the size of their receptive fields, suggesting that the pattern of tracer coupling may provide some index of the extent of electrical coupling. We studied this question by comparing the receptive field and tracer coupling size of dark-adapted horizontal cells recorded in the superfused, isolated retina-eyecup of the rabbit. Both the edge-to-edge receptive field and space constants (lambda) were computed for each cell using a long, narrow slit of light displaced across the retinal surface. Cells were subsequently labeled by iontophoretic injection of Neurobiotin. The axonless A-type horizontal cells showed extensive, homologous tracer coupling in groups greater than 1000 covering distances averaging about 2 mm. The axon-bearing B-type horizontal cells were less extensively tracer coupled, showing homologous coupling of the somatic endings in groups of about 100 cells spanning approximately 400 mu m and a separate homologous coupling of the axon terminal endings covering only about 275 mu m. Moreover, we observed a remarkable, linear relationship between the size of the receptive fields of each of the three horizontal cell endings and the magnitude of their tracer coupling. Our findings suggest that the extent of tracer coupling provides a strong, linear index of the magnitude of electrical current flow, as derived from receptive-field measures, across groups of coupled horizontal cells. These data thus provide the first direct evidence that the receptive-field size of horizontal cells is related to the extent of their coupling via gap junctions.