The cerebral hemispheres are specialized for different cognitive functions and receive divergent information from the sensory organs, so that the interaction between the hemispheres is a crucial aspect of perception and cognition. At the same time, the major fiber tract responsible for this interaction, the corpus callosum, shows a structural development across the lifespan which is over-proportional. That is, compared to changes in overall forebrain volume, the corpus callosum shows an accentuated growth during childhood, adolescence, and early adulthood, as well as pronounced decline in older age. However, this over-proportionality of growth and decline along with potential consequences for cognition, have been largely overlooked in empirical research. In the present study we systematically address the proportionality of callosal development in a large mixed cross-sectional and longitudinal sample (1867 datasets from 1014 unique participants), covering the human lifespan (age range 4–93 years), and examine the cognitive consequences of the observed changes. Relative corpus callosum thickness was measured at 60 segments along the midsagittal surface, and lifespan trajectories were clustered to identify callosal subsections of comparable lifespan development. While confirming the expected inverted u-shaped lifespan trajectories, we also found substantial regional variation. Compared with anterior clusters, the most posterior sections exhibited an accentuated growth during development which extends well into the third decade of life, and a protracted decline in older age which is delayed by about 10 years (starting mid to late 50s). We further showed that the observed longitudinal changes in relative thickness of the mid splenium significantly mediates age-related changes in tests assessing verbal knowledge and non-verbal visual-spatial abilities across the lifespan. In summary, we demonstrate that analyzing the proportionality of callosal growth and decline offers valuable insight into lifespan development of structural connectivity between the hemispheres, and suggests consequences for the cognitive development of perception and cognition.

脑半球专门用于不同的认知功能，并从感觉器官接收不同的信息，因此，半球之间的相互作用是感知和认知的关键方面。同时，造成这种相互作用的主要纤维束call体显示出整个寿命中的结构发展，这是过度比例的。也就是说，与总前脑体积的变化相比，call体在儿童期，青春期和成年早期表现出明显的增长，并且在老年人中明显下降。然而，这种过度增长和下降的比例以及对认知的潜在后果，在实证研究中已被大大忽略。在本研究中，我们系统地研究了大型混合横截面和纵向样本（来自1014个独特参与者的1867个数据集）中的愈伤组织发育的比例，该样本涵盖了人类的寿命（4-93岁），并检查了观察到的变化。沿矢状面中段的60个节段测量相对的体厚度，并对寿命轨迹进行聚类，以确定可比较寿命发展的call部分。在确认预期的倒U型寿命轨迹时，我们还发现了较大的区域差异。与前部簇相比，最后部在发育过程中表现出明显的增长，一直延伸到生命的第三个十年，以及年龄的持续下降，该下降被延迟了大约10年（从50年代中期到后期）。我们进一步表明，在评估整个寿命期间的言语知识和非语言视觉空间能力的测试中，观察到的脾中部相对厚度的纵向变化显着介导了与年龄相关的变化。总而言之，我们证明了分析愈伤组织生长和下降的比例可为半球之间结构连通性的寿命发展提供有价值的见解，并为感知和认知的认知发展提出建议。我们进一步表明，在评估整个寿命期间的言语知识和非语言视觉空间能力的测试中，观察到的脾中部相对厚度的纵向变化显着介导了与年龄相关的变化。总而言之，我们证明了分析愈伤组织生长和下降的比例可为半球之间结构连接的寿命发展提供有价值的见解，并提出感知和认知的认知发展的后果。我们进一步表明，在评估整个寿命期间的言语知识和非语言视觉空间能力的测试中，观察到的脾中部相对厚度的纵向变化显着介导了与年龄相关的变化。总而言之，我们证明了分析愈伤组织生长和下降的比例可为半球之间结构连通性的寿命发展提供有价值的见解，并为感知和认知的认知发展提出建议。