Homotypic constraints dominate positioning of on- and off-center beta retinal ganglion cells
Homotypic constraints dominate positioning of on- and off-center beta retinal ganglion cells
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DOI：
10.1017/s0952523805226147
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发表时间：
2005-11-01
影响因子：
1.9
通讯作者：
Troy, JB
中科院分区：
文献类型：
--
作者：
Eglen, SJ;Diggle, PJ;Troy, JB
猫的β视网膜神经节细胞(RGC)根据其对光的反应被分为中心上或中心外。这些位于中心和偏离中心的视网膜节细胞胞体在空间上呈规则的图案分布，称为视网膜马赛克。在本文中，我们通过分析RGC的地图并对这些模式进行模拟，研究了RGC在中心位置和偏离中心位置之间的空间相关性的性质。我们介绍了参数估计的原则性方法，以及评估不同假设的基于似然的技术。假设类型内和类型间的细胞之间的空间约束由两个单变量交互作用函数和一个双变量交互作用函数控制。通过对双变量交互作用函数的形状做出不同的假设，我们可以比较统计独立性假设和功能独立性替代假设，其中类型之间的交互作用仅限于防止Somal重叠。我们的发现表明，假设两种类型的RGC之间的功能独立，可能会产生中心上和中心外的βRGC的马赛克。相比之下，允许更一般形式的双变量交互作用函数并不能提高生成观测地图的可能性。因此，位于中心和偏离中心的βRGC可能只受到同型约束和物理约束，即没有两个相反类型的SoMA可以占据相同的位置。
Beta retinal ganglion cells (RGCs) of the cat are classified as either on-center or off-center, according to their response to light. The cell bodies of these on- and off-center RGCs are spatially distributed into regular patterns, known as retinal mosaics. In this paper, we investigate the nature of spatial dependencies between the positioning of on- and off-center RGCs by analysing maps of RGCs and simulating these patterns. We introduce principled approaches to parameter estimation, along with likelihood-based techniques to evaluate different hypotheses. Spatial constraints between cells within-type and between-type are assumed to be controlled by two univariate interaction functions and one bivariate interaction function. By making different assumptions on the shape of the bivariate interaction function, we can compare the hypothesis of statistical independence against the alternative hypothesis of functional independence, where interactions between type are limited to preventing somal overlap. Our findings suggest that the mosaics of on- and off-center beta RGCs are likely to be generated assuming functional independence between the two types. By contrast, allowing a more general form of bivariate interaction function did not improve the likelihood of generating the observed maps. On- and off-center beta RGCs are therefore likely to be positioned subject only to homotypic constraints and the physical constraint that no two somas of opposite type can occupy the same position.