Default-mode activity during a passive sensory task: Uncoupled from deactivation but impacting activation
Default-mode activity during a passive sensory task: Uncoupled from deactivation but impacting activation
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DOI：
10.1162/0898929042568532
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发表时间：
2004-11-01
影响因子：
3.2
通讯作者：
Menon, V
中科院分区：
文献类型：
--
作者：
Greicius, MD;Menon, V
去激活指的是，与高需求任务相比，低需求任务或休息时神经活动增加。Demand几个小组报告说，包括后扣带回皮质和内侧前额叶皮质在内的一组特定的大脑区域一直处于失活状态。综上所述，这些典型的失活大脑区域似乎构成了一个默认模式的大脑活动网络，在没有要求苛刻的外部任务的情况下占主导地位。用标准的去激活分析(休息时期与刺激时期)检查一个被动的、模块设计的感觉任务，我们证明默认模式的网络在一次运行中是不可检测的，在第二次运行中只有部分可检测到。然而，使用独立成分分析，我们能够在两次运行中检测到完整的默认模式网络，并证明在大多数受试者中，它在休息和刺激时期都持续存在，与任务波形分离，因此大多数情况下无法检测到去激活。我们还复制了一个较早的发现，即默认激活。默认模式网络包括海马体，这表明模式情景记忆被纳入默认模式认知处理。此外，我们还发现，受试者的默认模式活动与休息时期(以及在刺激时期“失活”)的相关性越大，该受试者对视觉和听觉刺激的激活程度就越大。我们得出结论，如果实验没有足够的挑战性，默认模式网络中的活动可能会持续到实验和休息时期。对默认模式活动的时间序列分析提供了一种测量模式任务参与受试者的程度，以及它是否足以中断由默认模式网络调节的过程--可能是认知的、内部产生的，并涉及情景记忆。
Deactivation refers to increased neural activity during low-demand tasks or rest compared with high-demand tasks. demand Several groups have reported that a particular set of brain regions, including the posterior cingulate cortex and the medial prefrontal cortex, among others, is consistently deactivated. Taken together, these typically deactivated brain regions appear to constitute a default-mode network of brain activity that predominates in the absence of a demanding external task. Examining a passive, block-design sensory task with a standard deactivation analysis ( rest epochs vs. stimulus epochs), we demonstrate that the default-mode network is undetectable in one run and only partially detectable in a second run. Using independent component analysis, however, we were able to detect the full default-mode network in both runs and to demonstrate that, in the majority of subjects, it persisted across both rest and stimulus epochs, uncoupled from the task waveform, and so mostly undetectable as de-deactivation. We also replicate an earlier finding that the default-activation. default-mode network includes the hippocampus suggesting that mode episodic memory is incorporated in default-mode cognitive processing. Furthermore, we show that the more a subject's default-mode activity was correlated with the rest epochs ( and "deactivated'' during stimulus epochs), the greater that subject's activation to the visual and auditory stimuli. We conclude that activity in the default-mode network may persist through both experimental and rest epochs if the experiment is not sufficiently challenging. Time-series analysis of default-mode activity provides a measure of the degree to which a mode task engages a subject and whether it is sufficient to interrupt the processes - presumably cognitive, internally generated, and involving episodic memory - mediated by the default-mode network.