Cerebral Blood Flow in Posterior Cortical Nodes of the Default Mode Network Decreases with Task Engagement but Remains Higher than in Most Brain Regions
Cerebral Blood Flow in Posterior Cortical Nodes of the Default Mode Network Decreases with Task Engagement but Remains Higher than in Most Brain Regions
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DOI：
10.1093/cercor/bhq090
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发表时间：
2011-01-01
期刊：
影响因子：
3.7
通讯作者：
Sullivan, Edith V.
中科院分区：
文献类型：
--
作者：
Pfefferbaum, Adolf;Chanraud, Sandra;Sullivan, Edith V.
功能神经成像研究提供了一致的证据，证明存在在静息状态下激活的内在大脑网络，以及在选择性认知需求时失活的内在大脑网络。与任务相关的默认模式网络的失活是否意味着相对于剩余大脑的活动受到抑制，或者仅仅是相对于其休息状态的活动减少，仍然存在争议。我们使用3D动脉自旋标记成像来检测休息时的局部脑血流量(CBF)，这是一个空间工作记忆任务，以及第二次休息。从静息到任务的局部CBF变化显示，扣带回后部、楔前后部和额叶内侧的CBF显著降低。统计参数映射连通性分析，在后扣带皮质有一个先验种子，产生了与经典的“默认模式网络”一致的失活连通性模式，以及与参与视觉空间任务解剖一致的激活连通性。与任务相关的脑血流量在楔前后部-下部相对于其前部和中部的大幅下降增加了楔前部的异质性的证据。在静息状态和任务完成时，扣带回后部和楔前下部也是脑血流量最高的区域。局部CBF的内在(静息)和诱发(任务)活动水平之间的差异可能代表着功能准备或储备容易受到影响灌流的条件的减少。
Functional neuroimaging studies provide converging evidence for existence of intrinsic brain networks activated during resting states and deactivated with selective cognitive demands. Whether task-related deactivation of the default mode network signifies depressed activity relative to the remaining brain or simply lower activity relative to its resting state remains controversial. We employed 3D arterial spin labeling imaging to examine regional cerebral blood flow (CBF) during rest, a spatial working memory task, and a second rest. Change in regional CBF from rest to task showed significant normalized and absolute CBF reductions in posterior cingulate, posterior-inferior precuneus, and medial frontal lobes. A Statistical Parametric Mapping connectivity analysis, with an a priori seed in the posterior cingulate cortex, produced deactivation connectivity patterns consistent with the classic "default mode network" and activation connectivity anatomically consistent with engagement in visuospatial tasks. The large task-related CBF decrease in posterior-inferior precuneus relative to its anterior and middle portions adds evidence for the precuneus' heterogeneity. The posterior cingulate and posterior-inferior precuneus were also regions of the highest CBF at rest and during task performance. The difference in regional CBF between intrinsic (resting) and evoked (task) activity levels may represent functional readiness or reserve vulnerable to diminution by conditions affecting perfusion.