Institute of Computational Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
Neural Systems Laboratory, Department of Health Sciences, Boston University, Boston, Massachusetts, United States of America.
PLoS Comput Biol. 2020 Oct 13;16(10):e1007991. doi: 10.1371/journal.pcbi.1007991. eCollection 2020 Oct.
The architectonic type principle conceptualizes structural connections between brain areas in terms of the relative architectonic differentiation of connected areas. It has previously been shown that spatio-temporal interactions between the time and place of neurogenesis could underlie multiple features of empirical mammalian connectomes, such as projection existence and the distribution of projection strengths. However, so far no mechanistic explanation for the emergence of typically observed laminar patterns of projection origins and terminations has been tested. Here, we expand an in silico model of the developing cortical sheet to explore which factors could potentially constrain the development of laminar projection patterns. We show that manipulations which rely solely on spatio-temporal interactions, namely the relative density of laminar compartments, a delay in the neurogenesis of infragranular layers relative to layer 1, and a delay in the neurogenesis of supragranular layers relative to infragranular layers, do not result in the striking correlation between supragranular contribution to projections and the relative differentiation of areas that is typically observed in the mammalian cortex. In contrast, we find that if we introduce systematic variation in cell-intrinsic properties, coupling them with architectonic differentiation, the resulting laminar projection patterns closely mirror the empirically observed patterns. We also find that the spatio-temporal interactions posited to occur during neurogenesis are necessary for the formation of the characteristic laminar patterns. Hence, our results indicate that the specification of the laminar patterns of projection origins may result from systematic variation in a number of cell-intrinsic properties, superimposed on the previously identified spatio-temporal interactions which are sufficient for the emergence of the architectonic type principle on the level of inter-areal connectivity in silico.
结构类型原则根据连接区域的相对结构分化来概念化大脑区域之间的结构连接。先前已经表明，神经发生的时间和地点之间的时空相互作用可以为经验哺乳动物连接组的多个特征提供基础，例如投射的存在和投射强度的分布。然而，到目前为止，还没有针对投射起源和终止的典型观察到的层状模式出现的机制解释进行测试。在这里，我们扩展了发育中的皮质板的计算机模型，以探索哪些因素可能限制层状投射模式的发展。我们表明，仅依赖时空相互作用的操作，即层状隔室的相对密度、相对于第 1 层的颗粒下层神经发生的延迟，以及相对于颗粒下层的颗粒上层神经发生的延迟，不会导致投射中颗粒上层的贡献与哺乳动物皮质中典型观察到的区域相对分化之间的显著相关性。相比之下，我们发现，如果我们引入细胞内在特性的系统变化，并将其与结构分化联系起来，那么由此产生的层状投射模式会非常接近经验观察到的模式。我们还发现，假定在神经发生过程中发生的时空相互作用对于形成特征性的层状投射模式是必要的。因此，我们的结果表明，投射起源的层状模式的指定可能是由于一系列细胞内在特性的系统变化，叠加在先前确定的时空相互作用上，这些相互作用足以在计算机水平上出现区域间连接的结构类型原则。
