Bloomfield Stewart A, Völgyi Béla
Department of Ophthalmology, New York University School of Medicine, 550 First Avenue, New York, NY 10016, USA.
Vision Res. 2004 Dec;44(28):3297-306. doi: 10.1016/j.visres.2004.07.012.
The AII amacrine cells are critical elements in the primary rod pathway of the mammalian retina, acting as an obligatory conduit of rod signals to both on- and off-center ganglion cells. In addition to the chemical synaptic circuitry they subserve, AII cells form two types of electrical synapses corresponding to gap junctions formed between neighboring AII cells as well as junctions formed between AII cells and on-center cone bipolar cells. Our recent results indicate that coupling between AII cells and cone bipolar cells forms an obligatory synapse for transmission of scotopic visual signals to on-center ganglion cells. In contrast, AII-AII cell coupling acts to maintain the sensitivity of the primary rod pathway by allowing for summation of synchronous activity and the attenuation of asynchronous background noise. Further, the conductance of AII-AII cell gap junctions is highly dynamic, regulated by ambient light conditions, thereby preserving the fidelity of rod signaling over the scotopic operating range from starlight to twilight.
AII无长突细胞是哺乳动物视网膜初级视杆通路中的关键元件，作为视杆信号传递至ON中心和OFF中心神经节细胞的必经通道。除了它们所支持的化学突触回路外，AII细胞形成两种类型的电突触，分别对应于相邻AII细胞之间形成的缝隙连接以及AII细胞与ON中心视锥双极细胞之间形成的连接。我们最近的结果表明，AII细胞与视锥双极细胞之间的耦合形成了一个将暗视觉信号传递至ON中心神经节细胞的必经突触。相比之下，AII-AII细胞耦合通过允许同步活动的总和以及异步背景噪声的衰减来维持初级视杆通路的敏感性。此外，AII-AII细胞缝隙连接的电导是高度动态的，受环境光条件调节，从而在从星光到黄昏的暗视觉工作范围内保持视杆信号的保真度。
