Keshavan Matcheri S, Diwadkar Vaibhav A, DeBellis Michael, Dick Elizabeth, Kotwal Rupali, Rosenberg David R, Sweeney John A, Minshew Nancy, Pettegrew Jay W
Western Psychiatric Institute and Clinic, University of Pittsburgh School of Medicine, PA 15213-2593, USA.
Life Sci. 2002 Mar 8;70(16):1909-22. doi: 10.1016/s0024-3205(02)01492-3.
The corpus callosum (CC) is the major commissure connecting the cerebral hemispheres and there is evidence of its continuing development into young adulthood [Ann. Neurol. 34 (1993) 71]. Yet, little is known about changes in the size and tissue characteristics of its sub-regions. The sub-regions of the CC (genu, body, isthmus and splenium) are topographically organized to carry interhemispheric fibres representing heteromodal and unimodal cortical brain regions. Studies of the development of each of these sub-regions can therefore provide insights into the time course of brain development. We assessed age-related changes in the size and the signal intensities (SI) of the subregions of the corpus callosum in the Magnetic Resonance Imaging (MRI) scans of a cross-sectional sample of 109 healthy young individuals aged 7-32 years. Age was significantly positively correlated with the size of the callosal sub-regions (with the exception of the isthmus). On the other hand, there was an age-related decrease in SI across all the CC sub-regions. The rates of CC regional size increases appeared to be most pronounced in childhood. By contrast, SI decreases occurred during childhood and adolescence but reached an asymptote during young adulthood. Finally, the observed size and SI changes were similar across CC sub-regions. The observed increases in CC size in conjunction with the decreases in signal intensity reflect continued maturation of the structure from childhood through young adulthood. An increase in axonal size may underlie growth in the size of the CC during childhood. The continued decrease in the CC signal intensity during adolescence may in addition be related to ongoing maturation of the axonal cytoskeleton. CC maturational changes appeared synchronous across sub-regions suggesting parallel maturation of diverse brain regions during childhood and adolescence.
胼胝体（CC）是连接大脑半球的主要连合纤维束，有证据表明其在青年期仍持续发育[《神经病学纪事》34卷（1993年）第71页]。然而，关于其亚区域大小和组织特征的变化却知之甚少。CC的亚区域（膝部、体部、峡部和压部）在拓扑结构上有组织地传导代表异模态和单模态皮质脑区的半球间纤维。因此，对这些亚区域各自发育情况的研究能够为脑发育的时间进程提供见解。我们在109名年龄在7至32岁的健康青年个体的横断面样本的磁共振成像（MRI）扫描中，评估了胼胝体亚区域的大小和信号强度（SI）与年龄相关的变化。年龄与胼胝体亚区域的大小显著正相关（峡部除外）。另一方面，所有CC亚区域的SI都随年龄下降。CC区域大小的增加速率在儿童期似乎最为显著。相比之下，SI下降发生在儿童期和青少年期，但在青年期达到稳定状态。最后，CC各亚区域观察到的大小和SI变化相似。观察到的CC大小增加以及信号强度下降反映了该结构从儿童期到青年期的持续成熟。儿童期CC大小的增长可能以轴突大小的增加为基础。青春期CC信号强度的持续下降可能还与轴突细胞骨架的持续成熟有关。CC的成熟变化在各亚区域似乎是同步的，表明儿童期和青少年期不同脑区平行成熟。
