Image processing begins in the retina, where neurons respond with graded voltage changes that must be converted into spikes. This conversion from 'analog' to 'digital' coding is a fundamental transformation carried out by the visual system, but the mechanisms are still not well understood. Recent work demonstrates that, in vertebrates, graded-to-spiking conversion of the visual signal begins in the axonal system of bipolar cells (BCs), which transmit visual information through ribbon-type synapses specialized for responding to graded voltage signals. Here, we explore the evidence for and against the idea that ribbon synapses also transmit digital information. We then discuss the potential costs and benefits of digitization at different stages of visual pathways in vertebrates and invertebrates.

中文翻译：

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早期视觉中的尖峰和带状突触

图像处理始于视网膜，神经元以分级电压变化做出反应，这些变化必须转化为尖峰。这种从“模拟”到“数字”编码的转换是视觉系统进行的基本转换，但其机制仍未得到很好的理解。最近的研究表明，在脊椎动物中，视觉信号的分级到尖峰转换始于双极细胞 (BC) 的轴突系统，其通过专门用于响应分级电压信号的带状突触传输视觉信息。在这里，我们探讨了支持和反对丝带突触也传输数字信息这一观点的证据。然后，我们讨论了脊椎动物和无脊椎动物视觉通路不同阶段数字化的潜在成本和收益。