University Hospital of Psychiatry, Department of Psychiatric Neurophysiology, Bern, Switzerland.
Neuroimage. 2011 Feb 14;54(4):3057-66. doi: 10.1016/j.neuroimage.2010.10.039. Epub 2010 Oct 20.
The Default Mode Network (DMN) is a higher order functional neural network that displays activation during passive rest and deactivation during many types of cognitive tasks. Accordingly, the DMN is viewed to represent the neural correlate of internally-generated self-referential cognition. This hypothesis implies that the DMN requires the involvement of cognitive processes, like declarative memory. The present study thus examines the spatial and functional convergence of the DMN and the semantic memory system. Using an active block-design functional Magnetic Resonance Imaging (fMRI) paradigm and Independent Component Analysis (ICA), we trace the DMN and fMRI signal changes evoked by semantic, phonological and perceptual decision tasks upon visually-presented words. Our findings show less deactivation during semantic compared to the two non-semantic tasks for the entire DMN unit and within left-hemispheric DMN regions, i.e., the dorsal medial prefrontal cortex, the anterior cingulate cortex, the retrosplenial cortex, the angular gyrus, the middle temporal gyrus and the anterior temporal region, as well as the right cerebellum. These results demonstrate that well-known semantic regions are spatially and functionally involved in the DMN. The present study further supports the hypothesis of the DMN as an internal mentation system that involves declarative memory functions.
默认模式网络（DMN）是一个高级别的功能神经网络，在被动休息时显示激活，在许多类型的认知任务中显示去激活。因此，DMN 被认为代表了内部产生的自我参照认知的神经相关性。这一假设意味着 DMN 需要涉及认知过程，如陈述性记忆。本研究因此检验了 DMN 和语义记忆系统的空间和功能收敛。使用主动块设计功能磁共振成像（fMRI）范式和独立成分分析（ICA），我们追踪了 DMN 和 fMRI 信号变化，这些变化是由视觉呈现的单词引发的语义、语音和感知决策任务引起的。我们的发现表明，在整个 DMN 单元和左半球 DMN 区域内，与两个非语义任务相比，语义任务的去激活程度较低，即背内侧前额叶皮层、前扣带皮层、后扣带回皮层、角回、颞中回和前颞叶区域，以及右小脑。这些结果表明，众所周知的语义区域在空间和功能上都参与了 DMN。本研究进一步支持了 DMN 作为一个内部思维系统的假设，该系统涉及陈述性记忆功能。
