Demb Jonathan B, Singer Joshua H
Department of Ophthalmology & Visual Sciences, Yale University School of Medicine, New Haven, Connecticut, USA.
Vis Neurosci. 2012 Jan;29(1):51-60. doi: 10.1017/S0952523811000368.
Amacrine cells represent the most diverse class of retinal neuron, comprising dozens of distinct cell types. Each type exhibits a unique morphology and generates specific visual computations through its synapses with a subset of excitatory interneurons (bipolar cells), other amacrine cells, and output neurons (ganglion cells). Here, we review the intrinsic and network properties that underlie the function of the most common amacrine cell in the mammalian retina, the AII amacrine cell. The AII connects rod and cone photoreceptor pathways, forming an essential link in the circuit for rod-mediated (scotopic) vision. As such, the AII has become known as the rod-amacrine cell. We, however, now understand that AII function extends to cone-mediated (photopic) vision, and AII function in scotopic and photopic conditions utilizes the same underlying circuit: AIIs are electrically coupled to each other and to the terminals of some types of ON cone bipolar cells. The direction of signal flow, however, varies with illumination. Under photopic conditions, the AII network constitutes a crossover inhibition pathway that allows ON signals to inhibit OFF ganglion cells and contributes to motion sensitivity in certain ganglion cell types. We discuss how the AII's combination of intrinsic and network properties accounts for its unique role in visual processing.
无长突细胞是视网膜神经元中种类最多样的一类，包含数十种不同的细胞类型。每种类型都具有独特的形态，并通过与一部分兴奋性中间神经元（双极细胞）、其他无长突细胞和输出神经元（神经节细胞）形成突触来产生特定的视觉计算。在这里，我们综述了哺乳动物视网膜中最常见的无长突细胞——AII无长突细胞功能的内在和网络特性。AII无长突细胞连接视杆和视锥光感受器通路，在视杆介导的（暗视）视觉回路中形成关键连接。因此，AII无长突细胞已被称为视杆无长突细胞。然而，我们现在了解到AII无长突细胞的功能扩展到视锥介导的（明视）视觉，并且在暗视和明视条件下AII无长突细胞的功能利用相同的基础回路：AII无长突细胞彼此之间以及与某些类型的ON视锥双极细胞的终末电耦合。然而，信号流动的方向随光照而变化。在明视条件下，AII无长突细胞网络构成一条交叉抑制通路，使ON信号能够抑制OFF神经节细胞，并有助于某些类型神经节细胞的运动敏感性。我们讨论了AII无长突细胞的内在和网络特性的组合如何解释其在视觉处理中的独特作用。
