A comparison of receptive-field and tracer-coupling size of amacrine and ganglion cells in the rabbit retina
A comparison of receptive-field and tracer-coupling size of amacrine and ganglion cells in the rabbit retina
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DOI：
10.1017/s0952523800011846
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发表时间：
1997-11-01
影响因子：
1.9
通讯作者：
Xin, DY
中科院分区：
文献类型：
--
作者：
Bloomfield, SA;Xin, DY
最近的研究表明，生物素化示踪剂生物胞素和神经生物素的细胞间运动揭示了哺乳动物视网膜中的无长突细胞和神经节细胞广泛耦合。这些示踪剂耦合的证明表明，由近端神经元（即无长突细胞和神经节细胞）形成的电网络可能是信号穿过内视网膜横向传播的基础。我们通过比较兔子暗适应、灌注、隔离视网膜眼杯中的感受野大小、树突域大小以及无长突细胞和神经节细胞的示踪剂耦合程度来研究这个问题。我们的结果表明，虽然近端神经元的中心感受野比其相应的树突直径大约 15%，但这种微小的差异可以通过电耦合以外的因素来解释，例如与组织学处理相关的组织收缩。然而，无长突细胞和神经节细胞的示踪剂耦合程度平均约为相应感受野大小的两倍。因此，单个近端神经元的感受野与其树突直径的匹配程度远高于其所属的示踪剂耦合细胞网络的大小。此规则的例外是 An：无长突细胞，其中心感受野是其树突直径大小的 2-3 倍，但与示踪剂耦合阵列的大小密切匹配。因此，除了所有细胞外，我们的数据表明近端神经元之间的示踪剂耦合与其感受野的扩大无关。那么，我们的结果没有提供电耦合的证据，或者至少表明视觉信号的广泛横向传播不会发生在近端哺乳动物视网膜中。
Recent studies have shown that amacrine and ganglion cells in the mammalian retina are extensively coupled as revealed by the intercellular movement of the biotinylated tracers biocytin and Neurobiotin. These demonstrations of tracer coupling suggest that electrical networks formed by proximal neurons (i.e. amacrine and ganglion cells) may underIie the lateral propagation of signals across the inner retina. We studied this question by comparing the receptive-field size, dendritic-field size, and extent of tracer coupling of amacrine and ganglion cells in the dark-adapted, superfused, isolated retina eyecup of the rabbit. Our results indicate that while the center-receptive fields of proximal neurons are approximately 15% larger than their corresponding dendritic diameters, this slight difference can be explained by factors other than electrical coupling such as tissue shrinkage associated with histological processing. However, the extent of tracer coupling of amacrine and ganglion cells was, on average, about twice the size of the corresponding receptive fields. Thus, the receptive field of an individual proximal neuron matched far more closely to its dendritic diameter than to the size of the tracer-coupled network of cells to which it belonged. The exception to this rule was the An: amacrine cells for which center-receptive fields were 2-3 times the size of their dendritic diameters but matched closely to the size of the tracer-coupled arrays. Thus, with the exception of All cells, our data indicate that tracer coupling between proximal neurons is not associated with an enlargement of their receptive fields. Our results, then, provide no evidence for electrical coupling or, at least, indicate that extensive lateral spread of visual signals does not occur in the proximal mammalian retina.