Department of Biological Structure, University of Washington, Seattle, WA 98195, USA.
Department of Neurobiology, Stanford University School of Medicine, Stanford, CA 94305, USA.
Cell Rep. 2018 Nov 20;25(8):2017-2026.e3. doi: 10.1016/j.celrep.2018.10.089.
Sensory processing can be tuned by a neuron's integration area, the types of inputs, and the proportion and number of connections with those inputs. Integration areas often vary topographically to sample space differentially across regions. Here, we highlight two visual circuits in which topographic changes in the postsynaptic retinal ganglion cell (RGC) dendritic territories and their presynaptic bipolar cell (BC) axonal territories are either matched or unmatched. Despite this difference, in both circuits, the proportion of inputs from each BC type, i.e., synaptic convergence between specific BCs and RGCs, remained constant across varying dendritic territory sizes. Furthermore, synapse density between BCs and RGCs was invariant across topography. Our results demonstrate a wiring design, likely engaging homotypic axonal tiling of BCs, that ensures consistency in synaptic convergence between specific BC types onto their target RGCs while enabling independent regulation of pre- and postsynaptic territory sizes and synapse number between cell pairs.
感觉处理可以通过神经元的整合区域、输入的类型以及与这些输入的连接的比例和数量来调节。整合区域通常在地形上差异很大，以在不同区域对空间进行抽样。在这里，我们强调了两个视觉回路，在后突触视网膜神经节细胞 (RGC) 树突领域及其前突触双极细胞 (BC) 轴突领域中存在着匹配或不匹配的地形变化。尽管存在这种差异，但在这两个回路中，来自每种 BC 类型的输入比例，即特定 BC 和 RGC 之间的突触汇聚，在不同的树突领域大小下保持不变。此外，BC 和 RGC 之间的突触密度在地形上是不变的。我们的结果表明了一种布线设计，可能涉及 BC 的同型轴突平铺，从而确保特定 BC 类型与目标 RGC 之间的突触汇聚的一致性，同时能够独立调节细胞对之间的前突触和后突触领域大小和突触数量。
