Queensland Brain Institute, University of Queensland, Brisbane, QLD, 4072, Australia.
Imaging Genetics Center, University of Southern California, Los Angeles, CA, 90032, USA.
Brain Struct Funct. 2019 Nov;224(8):2805-2821. doi: 10.1007/s00429-019-01931-8. Epub 2019 Aug 19.
Comparing estimates of the amount of genetic and environmental variance for different brain structures may elucidate differences in the genetic architecture or developmental constraints of individual brain structures. However, most studies compare estimates of relative genetic (heritability) and environmental variance in brain structure, which do not reflect differences in absolute variance between brain regions. Here we used a population sample of young adult twins and singleton siblings of twins (n = 791; M = 23 years, Queensland Twin IMaging study) to estimate the absolute genetic and environmental variance, standardised by the phenotypic mean, in the size of cortical, subcortical, and ventricular brain structures. Mean-standardised genetic variance differed widely across structures [23.5-fold range 0.52% (hippocampus) to 12.28% (lateral ventricles)], but the range of estimates within cortical, subcortical, or ventricular structures was more moderate (two to fivefold range). There was no association between mean-standardised and relative measures of genetic variance (i.e., heritability) in brain structure volumes. We found similar results in an independent sample (n = 1075, M = 29 years, Human Connectome Project). These findings open important new lines of enquiry: namely, understanding the bases of these variance patterns, and their implications regarding the genetic architecture, evolution, and development of the human brain.
比较不同脑结构遗传和环境方差的估计值可以阐明个体脑结构遗传结构或发育限制的差异。然而，大多数研究比较脑结构遗传（遗传性）和环境方差的相对估计值，这些估计值不能反映脑区之间绝对方差的差异。在这里，我们使用年轻成年双胞胎和双胞胎单胞胎兄弟姐妹的人群样本（n=791；M=23 岁，昆士兰双胞胎成像研究）来估计皮质、皮质下和脑室脑结构大小的遗传和环境方差的绝对标准值。结构之间的平均标准遗传方差差异很大[范围为 0.52%（海马体）至 12.28%（侧脑室），23.5 倍]，但皮质、皮质下或脑室结构内的估计值范围更为适中（两倍至五倍）。脑结构体积的平均标准遗传方差与遗传方差（即遗传力）的相对测量值之间没有关联。我们在一个独立的样本（n=1075，M=29 岁，人类连接体计划）中发现了类似的结果。这些发现开辟了新的研究方向：即了解这些方差模式的基础，以及它们对人类大脑遗传结构、进化和发育的影响。
