Benjamin Christopher, Lieberman Daniel A, Chang Maria, Ofen Noa, Whitfield-Gabrieli Sue, Gabrieli John D E, Gaab Nadine
Laboratories of Cognitive Neuroscience, Developmental Medicine Center, Children's Hospital Boston Boston, MA, USA.
Front Hum Neurosci. 2010 Dec 1;4:218. doi: 10.3389/fnhum.2010.00218. eCollection 2010.
The default mode network (DMN) refers to regional brain activity that is greater during rest periods than during attention-demanding tasks; many studies have reported DMN alterations in patient populations. It has also been shown that the DMN is suppressed by scanner background noise (SBN), which is the noise produced by functional magnetic resonance imaging (fMRI). However, it is unclear whether different approaches to "rest" in the noisy MR environment can alter the DMN and constitute a confound in studies investigating the DMN in particular patient populations (e.g., individuals with schizophrenia, Alzheimer's disease). We examined 27 healthy adult volunteers who completed an fMRI experiment with three different instructions for rest: (1) relax and be still, (2) attend to SBN, or (3) ignore SBN. Region of interest analyses were performed to determine the influence of rest period instructions on core regions of the DMN and DMN regions previously reported to be altered in patients with or at risk for Alzheimer's disease or schizophrenia. The dorsal medial prefrontal cortex (dmPFC) exhibited greater activity when specific resting instructions were given (i.e., attend to or ignore SBN) compared to when non-specific resting instructions were given. Condition-related differences in connectivity were also observed between regions of the dmPFC and inferior parietal/posterior superior temporal cortex. We conclude that rest period instructions and SBN levels should be carefully considered for fMRI studies on the DMN, especially studies on clinical populations and groups that may have different approaches to rest, such as first-time research participants and children.
默认模式网络（DMN）是指在休息期间比在需要注意力的任务期间大脑活动更强的区域；许多研究报告了患者群体中DMN的改变。研究还表明，DMN会受到扫描仪背景噪声（SBN）的抑制，SBN是功能磁共振成像（fMRI）产生的噪声。然而，尚不清楚在嘈杂的磁共振环境中不同的“休息”方式是否会改变DMN，并在研究特定患者群体（如精神分裂症、阿尔茨海默病患者）的DMN时构成混淆因素。我们对27名健康成年志愿者进行了研究，他们完成了一项fMRI实验，实验中有三种不同的休息指导语：（1）放松并保持静止，（2）关注SBN，或（3）忽略SBN。进行了感兴趣区域分析，以确定休息期指导语对DMN核心区域以及先前报道在阿尔茨海默病或精神分裂症患者或有患病风险的个体中发生改变的DMN区域的影响。与给予非特定休息指导语时相比，当给予特定的休息指导语（即关注或忽略SBN）时，背内侧前额叶皮层（dmPFC）表现出更强的活动。在dmPFC与顶下叶/颞上后皮层区域之间也观察到了与条件相关的连通性差异。我们得出结论，对于关于DMN的fMRI研究，尤其是对临床人群以及可能有不同休息方式的群体（如首次参与研究的参与者和儿童）的研究，应仔细考虑休息期指导语和SBN水平。
