Danielsen V M, Vidal-Piñeiro D, Mowinckel A M, Sederevicius D, Fjell A M, Walhovd K B, Westerhausen R
Center for Lifespan Changes in Brain and Cognition (LCBC), Department of Psychology, University of Oslo, Norway.
Center for Lifespan Changes in Brain and Cognition (LCBC), Department of Psychology, University of Oslo, Norway; Department of Radiology and Nuclear Medicine, Oslo University Hospital, Norway.
Cortex. 2020 Sep;130:127-141. doi: 10.1016/j.cortex.2020.05.020. Epub 2020 Jun 14.
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.
大脑半球专门负责不同的认知功能，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，负责这种相互作用的主要纤维束——胼胝体，在整个生命周期中呈现出过度增长的结构发育。也就是说，与前脑总体积的变化相比，胼胝体在儿童期、青少年期和成年早期呈现出加速生长，而在老年期则明显衰退。然而，这种生长和衰退的过度比例以及对认知的潜在影响，在实证研究中很大程度上被忽视了。在本研究中，我们在一个大型的混合横断面和纵向样本（来自1014名独特参与者的1867个数据集）中系统地研究了胼胝体发育的比例，该样本涵盖了人类的整个生命周期（年龄范围为4至93岁），并研究了观察到的变化对认知的影响。沿着矢状中面在60个节段测量相对胼胝体厚度，并对生命周期轨迹进行聚类，以识别具有可比生命周期发育的胼胝体亚部分。在确认预期的倒U形生命周期轨迹的同时，我们还发现了显著的区域差异。与前部簇相比，最后部的节段在发育过程中呈现出加速生长，这种生长一直持续到生命的第三个十年，而在老年期则呈现出长期衰退，衰退延迟了约10年（从50多岁中期到后期开始）。我们进一步表明，观察到的胼胝体中部相对厚度的纵向变化在很大程度上介导了整个生命周期中评估言语知识和非言语视觉空间能力的测试中与年龄相关的变化。总之，我们证明，分析胼胝体生长和衰退的比例为半球之间结构连接的生命周期发育提供了有价值的见解，并暗示了对感知和认知的认知发展的影响。
