La Christian, Mossahebi Pouria, Nair Veena A, Bendlin Barbara B, Birn Rasmus, Meyerand Mary E, Prabhakaran Vivek
Neuroscience Training Program, University of Wisconsin-MadisonMadison, WI, USA; Department of Radiology, University of Wisconsin-MadisonMadison, WI, USA.
Department of Radiology, University of Wisconsin-Madison Madison, WI, USA.
Front Aging Neurosci. 2015 Dec 24;7:237. doi: 10.3389/fnagi.2015.00237. eCollection 2015.
Healthy aging is associated with brain changes that reflect an alteration to a functional unit in response to the available resources and architecture. Even before the onset of noticeable cognitive decline, the neural scaffolds underlying cognitive function undergo considerable change. Prior studies have suggested a disruption of the connectivity pattern within the "default-mode" network (DMN), and more specifically a disruption of the anterio-posterior connectivity. In this study, we explored the effects of aging on within-network connectivity of three DMN subnetworks: a posterior DMN (pDMN), an anterior DMN (aDMN), and a ventral DMN (vDMN); as well as between-network connectivity during resting-state. Using groupICA on 43 young and 43 older healthy adults, we showed a reduction of network co-activation in two of the DMN subnetworks (pDMN and aDMN) and demonstrated a difference in between-component connectivity levels. The older group exhibited more numerous high-correlation pairs (Pearson's rho > 0.3, Number of comp-pairs = 46) in comparison to the young group (Number of comp-pairs = 34), suggesting a more connected/less segregated cortical system. Moreover, three component-pairs exhibited statistically significant differences between the two populations. Visual areas V2-V1 and V2-V4 were more correlated in the older adults, while aDMN-pDMN correlation decreased with aging. The increase in the number of high-correlation component-pairs and the elevated correlation in the visual areas are consistent with the prior hypothesis that aging is associated with a reduction of functional segregation. However, the aDMN-pDMN dis-connectivity may be occurring under a different mechanism, a mechanism more related to a breakdown of structural integrity along the anterio-posterior axis.
健康衰老与大脑变化相关，这些变化反映了功能单元为响应可用资源和结构而发生的改变。甚至在明显的认知衰退开始之前，认知功能背后的神经支架就会发生相当大的变化。先前的研究表明，“默认模式”网络（DMN）内的连接模式受到破坏，更具体地说是前后连接受到破坏。在本研究中，我们探讨了衰老对三个DMN子网络（后DMN（pDMN）、前DMN（aDMN）和腹侧DMN（vDMN））内网络连接性的影响，以及静息状态下网络间的连接性。通过对43名年轻和43名年长健康成年人进行组独立成分分析（groupICA），我们发现两个DMN子网络（pDMN和aDMN）中的网络共激活减少，并证明了成分间连接水平的差异。与年轻组（成分对数量 = 34）相比，年长组表现出更多的高相关对（皮尔逊相关系数>0.3，成分对数量 = 46），表明皮质系统连接性更强/隔离性更弱。此外，两组人群之间的三个成分对表现出统计学上的显著差异。年长成年人的视觉区域V2-V1和V2-V4之间的相关性更高，而aDMN-pDMN相关性随衰老而降低。高相关成分对数量的增加和视觉区域相关性的升高与先前的假设一致，即衰老与功能隔离的减少有关。然而，aDMN-pDMN的断开连接可能是在不同的机制下发生的，这种机制更与沿前后轴的结构完整性破坏有关。
