School of Mathematical and Statistical Sciences, University of Galway, University Road, Galway, Ireland.
School of Mathematical and Statistical Sciences, University of Galway, University Road, Galway, Ireland.
Acta Biomater. 2023 Oct 1;169:66-87. doi: 10.1016/j.actbio.2023.07.040. Epub 2023 Jul 27.
This review addresses the acute need to acknowledge the mechanical heterogeneity of brain matter and to accurately calibrate its local viscoelastic material properties accordingly. Specifically, it is important to compile the existing and disparate literature on attenuation power-laws and dispersion to make progress in wave physics of brain matter, a field of research that has the potential to explain the mechanisms at play in diffuse axonal injury and mild traumatic brain injury in general. Currently, viscous effects in the brain are modelled using Prony-series, i.e., a sum of decaying exponentials at different relaxation times. Here we collect and synthesise the Prony-series coefficients appearing in the literature for twelve regions: brainstem, basal ganglia, cerebellum, corona radiata, corpus callosum, cortex, dentate gyrus, hippocampus, thalamus, grey matter, white matter, homogeneous brain, and for eight different mammals: pig, rat, human, mouse, cow, sheep, monkey and dog. Using this data, we compute the fractional-exponent attenuation power-laws for different tissues of the brain, the corresponding dispersion laws resulting from causality, and the averaged Prony-series coefficients. STATEMENT OF SIGNIFICANCE: Traumatic brain injuries are considered a silent epidemic and finite element methods (FEMs) are used in modelling brain deformation, requiring access to viscoelastic properties of brain. To the best of our knowledge, this work presents 1) the first multi-frequency viscoelastic atlas of the heterogeneous brain, 2) the first review focusing on viscoelastic modelling in both FEMs and experimental works, 3) the first attempt to conglomerate the disparate existing literature on the viscoelastic modelling of the brain and 4) the largest collection of viscoelastic parameters for the brain (212 different Prony-series spanning 12 different tissues and 8 different animal surrogates). Furthermore, this work presents the first brain atlas of attenuation power-laws essential for modelling shear waves in brain.
这篇综述文章迫切需要认识到脑物质的力学异质性，并相应地准确校准其局部黏弹性材料特性。具体来说，重要的是要汇集关于衰减幂律和频散的现有和分散的文献，以便在脑物质的波动物理领域取得进展，这个研究领域有潜力解释弥漫性轴索损伤和轻度创伤性脑损伤的一般机制。目前，脑内的粘性效应是通过 Prony 级数来建模的，即不同弛豫时间的衰减指数之和。在这里，我们收集并综合了文献中出现的 Prony 级数系数，共涉及 12 个区域：脑干、基底神经节、小脑、放射冠、胼胝体、皮层、齿状回、海马体、丘脑、灰质、白质、均匀脑，以及 8 种不同的哺乳动物：猪、大鼠、人类、小鼠、牛、绵羊、猴子和狗。利用这些数据，我们计算了不同脑组织的分数指数衰减幂律、因果关系产生的相应频散律，以及平均 Prony 级数系数。
外伤性脑损伤被认为是一种无声的流行疾病，有限元方法（FEM）用于模拟脑变形，需要获得脑的黏弹性特性。据我们所知，这项工作有以下几个创新点：1）首次提出了不均匀脑的多频黏弹性图谱；2）首次关注 FEM 和实验工作中的黏弹性建模；3）首次尝试整合关于脑黏弹性建模的现有分散文献；4）首次收集了 212 个不同的 Prony 级数的脑黏弹性参数，涵盖了 12 种不同的组织和 8 种不同的动物替代物。此外，这项工作还首次提出了建模脑剪切波所必需的衰减幂律的脑图谱。
