How do horizontal cells 'talk' to cone photoreceptors? Different levels of complexity at the cone-horizontal cell synapse
How do horizontal cells 'talk' to cone photoreceptors? Different levels of complexity at the cone-horizontal cell synapse
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DOI：
10.1113/jp274177
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发表时间：
2017-08-15
影响因子：
5.5
通讯作者：
Schubert, Timm
中科院分区：
文献类型：
--
作者：
Chapot, Camille A.;Euler, Thomas;Schubert, Timm
视网膜的第一个突触在视觉系统中起着重要的作用。由于其重要性，它以尽可能高的准确度和精度对来自外部世界的信息进行编码至关重要。视锥光感受器轴突末端包含许多单独的突触位点，每个突触位点由称为“带状物”的突触前结构表示。这些突触既高度复杂又保守。每个带状物将光信号中继到一个ON锥双极细胞和几个OFF锥双极细胞，而来自GABA能中间神经元（水平细胞）的两个树突状突起通过并行反馈机制调节锥输出。这三个伙伴在一个突触中的存在引起了许多问题，其解剖和功能的复杂性仍然只是部分了解。然而，这种突触的理解最近已经演变，作为在理解树突信号处理及其在促进全球与局部信号传导的作用方面取得进展的结果。事实上，对于下游视网膜网络，水平细胞中的树突状处理可能是必不可少的，因为它们必须支持重要的功能操作，例如对比度增强，这需要光感受器阵列的空间平均，同时保留准确的空间信息。在这里，我们回顾最近取得的进展，更好地了解锥突触，强调水平细胞功能，并讨论为什么这种复杂性可能是必要的早期视觉处理。
The first synapse of the retina plays a fundamental role in the visual system. Due to its importance, it is critical that it encodes information from the outside world with the greatest accuracy and precision possible. Cone photoreceptor axon terminals contain many individual synaptic sites, each represented by a presynaptic structure called a 'ribbon'. These synapses are both highly sophisticated and conserved. Each ribbon relays the light signal to one ON cone bipolar cell and several OFF cone bipolar cells, while two dendritic processes from a GABAergic interneuron, the horizontal cell, modulate the cone output via parallel feedback mechanisms. The presence of these three partners within a single synapse has raised numerous questions, and its anatomical and functional complexity is still only partially understood. However, the understanding of this synapse has recently evolved, as a consequence of progress in understanding dendritic signal processing and its role in facilitating global versus local signalling. Indeed, for the downstream retinal network, dendritic processing in horizontal cells ay be essential, as they must support important functional operations such as contrast enhancement, which requires spatial averaging of the photoreceptor array, while at the same time preserving accurate spatial information. Here, we review recent progress made towards a better understanding of the cone synapse, with an emphasis on horizontal cell function, and discuss why such complexity might be necessary for early visual processing.