Center for Psychosocial Medicine, Department of General Psychiatry, University of Heidelberg, Germany.
Exp Neurol. 2012 Sep;237(1):191-8. doi: 10.1016/j.expneurol.2012.06.014. Epub 2012 Jun 25.
The default-mode network (DMN) refers to as a set of brain regions which are active when the brain does not engage in a cognitive task and which are deactivated with task-related cognitive effort. Altered function of the DMN has been associated with a decline of cognition in several neurodegenerative diseases and related at-risk conditions. In Huntington's disease, an autosomal dominant inherited neurodegenerative disorder, several studies so far have shown abnormal task-related brain activation patterns even in preclinical carriers of the Huntington's disease gene mutation (preHD). To date, however, the functional integrity of the DMN has not been addressed in this population. The aim of this study was to study the functional connectivity of the DMN in 18 preHD and 18 healthy controls who underwent functional magnetic resonance imaging during an attention task. A group independent component analysis identified spatiotemporally distinct patterns of two DMN subsystems. The spatial distribution of these components in preHD was similar to controls. However, preHD showed lower subsystem-specific connectivity in the anterior medial prefrontal cortex, the left inferior parietal and the posterior cingulate cortex (p<0.05, cluster-corrected). Connectivity between the two DMN subsystems was increased in preHD compared to controls. In preHD individuals lower functional connectivity of the left inferior parietal cortex was associated with shorter reaction times in the attention task. This suggests that some functionally critical regions of the DMN may have to remain active to maintain or optimise cognitive performance in preHD.
默认模式网络（DMN）是指当大脑不参与认知任务时活跃的一组脑区，而当大脑进行与任务相关的认知努力时则会被抑制。DMN 功能的改变与几种神经退行性疾病和相关的高危状态下认知能力的下降有关。在亨廷顿病（一种常染色体显性遗传的神经退行性疾病）中，到目前为止，已有几项研究表明，即使在亨廷顿病基因突变（preHD）的临床前携带者中，也存在异常的与任务相关的大脑激活模式。然而，迄今为止，尚未在该人群中研究 DMN 的功能完整性。本研究旨在研究 18 名 preHD 和 18 名健康对照者在进行注意力任务时的功能磁共振成像的 DMN 功能连接。组独立成分分析确定了两个 DMN 子系统的时空上不同的模式。这些成分在 preHD 中的空间分布与对照组相似。然而，preHD 在前内侧前额叶皮层、左顶下小叶和后扣带回皮层的子系统特异性连接较低（p<0.05，簇校正）。与对照组相比，preHD 之间的两个 DMN 子系统的连接增加。在 preHD 个体中，左顶下小叶的功能连接降低与注意力任务中的反应时间缩短有关。这表明，DMN 的一些功能关键区域可能需要保持活跃，以维持或优化 preHD 的认知表现。
