Department of Pediatrics, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan.
Dev Neurosci. 2012;34(6):477-87. doi: 10.1159/000345152. Epub 2012 Dec 21.
Brain development during early life in healthy individuals is rapid and dynamic, indicating that this period plays a very important role in neural and functional development. The frontal and temporal lobes are known to play a particularly important role in cognition. The study of healthy frontal and temporal lobe development in children is therefore of considerable importance. A better understanding of how these brain regions develop could also aid in the diagnosis and treatment of neurodevelopmental disorders. Some developmental studies have used magnetic resonance imaging (MRI) to examine infant brains, but it remains the case that relatively little is known about cortical brain development in the first few years of life. In the present study we examined whole brain, temporal lobe and frontal lobe developmental trajectories from infancy to early adulthood in healthy individuals, considering gender and brain hemisphere differences. We performed a cross-sectional, longitudinal morphometric MRI study of 114 healthy individuals (54 females and 60 males) aged 1 month to 25 years old (mean age ± SD 8.8 ± 6.9). We measured whole brain, temporal and frontal lobe gray matter (GM)/white matter (WM) volumes, following previously used protocols. There were significant non-linear age-related volume changes in all regions. Peak ages of whole brain, temporal lobe and frontal lobe development occurred around pre-adolescence (9-12 years old). GM volumes for all regions increased significantly as a function of age. Peak age was nevertheless lobe specific, with a pattern of earlier peak ages for females in both temporal and frontal lobes. Growth change in whole brain GM volume was larger in males than in females. However, GM volume growth changes for the temporal and frontal lobes showed a somewhat different pattern. GM volume for both temporal and frontal lobes showed a greater increase in females until around 5-6 years old, at which point this tendency reversed (GM volume changes in males became greater), with male GM volume increasing for a longer time than that of females. WM volume growth changes were similar across regions, all increasing rapidly until early childhood but slowing down thereafter. All regions displayed significant rightward volumetric asymmetry regardless of sex. Furthermore, the right temporal and frontal lobes showed a greater volumetric increase than the left for the first several years, with this tendency reversing at around 6 years of age. In addition, the left frontal and temporal lobes increased in volume for a longer period of time. Taken together, these findings indicated that brain developmental trajectories differ depending on brain region, sex and brain hemisphere. Gender-related factors such as sex hormones and functional laterality may affect brain development.
在健康个体中，早期的大脑发育是迅速而动态的，这表明这一时期在神经和功能发育中起着非常重要的作用。额叶和颞叶被认为在认知中起着特别重要的作用。因此，研究儿童健康的额叶和颞叶发育具有重要意义。更好地了解这些脑区的发育过程，也有助于神经发育障碍的诊断和治疗。一些发展研究使用磁共振成像（MRI）来检查婴儿的大脑，但在生命的头几年，人们对皮质脑发育的了解仍然相对较少。在本研究中，我们考虑到性别和大脑半球的差异，研究了健康个体从婴儿期到成年早期的全脑、颞叶和额叶发育轨迹。我们对 114 名 1 个月至 25 岁（平均年龄±标准差 8.8±6.9）的健康个体进行了横断面、纵向形态磁共振成像研究。我们按照先前使用的方案测量了全脑、颞叶和额叶的灰质（GM）/白质（WM）体积。所有区域都有显著的非线性年龄相关的体积变化。全脑、颞叶和额叶发育的峰值年龄出现在青春期前（9-12 岁）。所有区域的 GM 体积都随年龄显著增加。然而，峰值年龄是特定于叶的，女性颞叶和额叶的峰值年龄都较早。全脑 GM 体积的生长变化在男性中大于女性。然而，颞叶和额叶的 GM 体积生长变化表现出不同的模式。女性的颞叶和额叶 GM 体积增加更大，直到大约 5-6 岁，此时这种趋势发生逆转（男性 GM 体积的变化更大），男性 GM 体积的增加时间比女性长。WM 体积的生长变化在各个区域都相似，在儿童早期之前迅速增加，但此后减缓。所有区域无论性别如何都表现出显著的右侧体积不对称。此外，右侧颞叶和额叶在前几年的体积增加大于左侧，这种趋势在 6 岁左右发生逆转。此外，左侧额叶和颞叶的体积增加时间更长。总之，这些发现表明，脑发育轨迹因脑区、性别和大脑半球而异。性别相关因素，如性激素和功能偏侧性，可能会影响大脑发育。
