Numerical investigation of biomechanically coupled growth in cortical folding
Numerical investigation of biomechanically coupled growth in cortical folding
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DOI：
10.1007/s10237-020-01400-w
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发表时间：
2020-11
影响因子：
3.5
通讯作者：
Shuolun Wang;Nagehan Demirci;Maria A. Holland
中科院分区：
文献类型：
--
作者：
Shuolun Wang;Nagehan Demirci;Maria A. Holland
皮质折叠-形成皮质特有的脑回(丘陵)和沟(谷)的过程-是一个高度动态的过程，是基因表达、细胞机制和机械力相互作用的结果。像许多其他细胞一样，神经元对机械环境很敏感。因此，在皮质折叠开始后，皮质生长可能不会均匀地发生在脑回和脑沟中，这伴随着周围组织的拉伸和压缩模式。在这里，作为我们以前工作的扩展，我们引入了一个生物力学耦合生长模型来研究生物生长和机械线索在脑发育过程中相互作用的重要性。我们早期对皮质生长的模拟是由一个均匀生长的皮质连接到一个有弹性的皮质下层组成的。在这里，我们让皮质生长的进化依赖于一个几何量--皮质的平均曲率--以实现脑回或脑沟的优先生长。与流行的前图案化假说相反，我们的模型将不均匀的皮质生长视为折叠的结果，而不是原因。通过编写用户自定义材料子程序(VUMAT)，在商用有限元软件ABAQUS/EXPLICIT中通过编写用户自定义材料子程序(VUMAT)对模型进行了数值实现。我们的模拟表明，脑回-沟厚度变化是低刚度比所特有的现象。与通过一致的采样方案测量的人脑皮质厚度相比，我们具有相似皮质和皮质下硬度的模拟表明，脑回的皮质生长比脑沟更高。
Cortical folding—the process of forming the characteristic gyri (hills) and sulci (valleys) of the cortex—is a highly dynamic process that results from the interaction between gene expression, cellular mechanisms, and mechanical forces. Like many other cells, neurons are sensitive to their mechanical environment. Because of this, cortical growth may not happen uniformly throughout gyri and sulci after the onset of cortical folding, which is accompanied by patterns of tension and compression in the surrounding tissue. Here, as an extension of our previous work, we introduce a biomechanically coupled growth model to investigate the importance of interaction between biological growth and mechanical cues during brain development. Our earlier simulations of cortical growth consisted of a homogeneous growing cortex attached to an elastic subcortex. Here, we let the evolution of cortical growth depend on a geometrical quantity—the mean curvature of the cortex—to achieve preferential growth in either gyri or sulci. As opposed to the popular pre-patterning hypothesis, our model treats inhomogeneous cortical growth as the result of folding rather than the cause. The model is implemented numerically in a commercial finite element software Abaqus/Explicit in Abaqus reference manuals, Dassault Systemes Simulia, Providence (2019) by writing user-defined material subroutine (VUMAT). Our simulations show that gyral–sulcal thickness variations are a phenomenon particular to low stiffness ratios. In comparison with cortical thickness measurements ofhuman brains via a consistent sampling scheme, our simulations with similar cortical and subcortical stiffnesses suggest that cortical growth is higher in gyri than in sulci.