Cortical networks for working memory and executive function sustain the conscious resting state in man

Groupe d'Imagerie Neurofonctionnelle, UMR6095, CNRS, LEA, Université de Caen, Université 5, Paris, France.
Brain Research Bulletin (Impact Factor: 2.72). 03/2001; 54(3):287-98. DOI: 10.1016/S0361-9230(00)00437-8
Source: PubMed


The cortical anatomy of the conscious resting state (REST) was investigated using a meta-analysis of nine positron emission tomography (PET) activation protocols that dealt with different cognitive tasks but shared REST as a common control state. During REST, subjects were in darkness and silence, and were instructed to relax, refrain from moving, and avoid systematic thoughts. Each protocol contrasted REST to a different cognitive task consisting either of language, mental imagery, mental calculation, reasoning, finger movement, or spatial working memory, using either auditory, visual or no stimulus delivery, and requiring either vocal, motor or no output. A total of 63 subjects and 370 spatially normalized PET scans were entered in the meta-analysis. Conjunction analysis revealed a network of brain areas jointly activated during conscious REST as compared to the nine cognitive tasks, including the bilateral angular gyrus, the left anterior precuneus and posterior cingulate cortex, the left medial frontal and anterior cingulate cortex, the left superior and medial frontal sulcus, and the left inferior frontal cortex. These results suggest that brain activity during conscious REST is sustained by a large scale network of heteromodal associative parietal and frontal cortical areas, that can be further hierarchically organized in an episodic working memory parieto-frontal network, driven in part by emotions, working under the supervision of an executive left prefrontal network.

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    • "Extensive neuroimaging research has identified a set of brain regions that displays relative deactivation during goal-driven, attention demanding paradigms (Binder et al., 1999; Mazoyer et al., 2001; Shulman et al., 1997). Despite the difficulty in assigning functional significance to these observations, the detected activity in the posterior cingulate, medial prefrontal cortices and bilateral angular gyri has been attributed to a " default mode of brain function " (Raichle et al., 2001), prominent in the absence of any external task demands (Gusnard and Raichle, 2001; Gusnard et al., 2001). "
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    ABSTRACT: Initially described as task-induced deactivations during goal-directed paradigms of high attentional load, the unresolved functionality of default mode regions has long been assumed to interfere with task performance. However, recent evidence suggests a potential default mode network involvement in fulfilling cognitive demands. We tested this hypothesis in a finger opposition paradigm with task and fixation periods which we compared with an independent resting state scan using functional magnetic resonance imaging and a comprehensive analysis pipeline including activation, functional connectivity, behavioural and graph theoretical assessments. The results indicate task specific changes in the default mode network topography. Behaviourally, we show that increased connectivity of the posterior cingulate cortex with the left superior frontal gyrus predicts faster reaction times. Moreover, interactive and dynamic reconfiguration of the default mode network regions' functional connections illustrate their involvement with the task at hand with higher-level global parallel processing power, yet preserved small-world architecture in comparison with rest. These findings demonstrate that the default mode network does not disengage during this paradigm, but instead may be involved in task relevant processing. Copyright © 2015. Published by Elsevier Inc.
    NeuroImage 07/2015; 122. DOI:10.1016/j.neuroimage.2015.07.053 · 6.36 Impact Factor
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    • "These primary nodes of the DMN are functionally connected, meaning they exhibit concerted fluctuations during functional tasks. The DMN's robustness has been established both functionally (Shulman et al., 1997; Gusnard and Raichle, 2001; Mazoyer et al., 2001; Raichle et al., 2001; detection of individuals at risk for AD. Most recently, work by Balthazar et al. (2014) found that by using the PCC as a seed region for DMN functional connectivity analysis, early AD patients could be distinguished from healthy controls with a sensitivity of 77.3 and 70% specificity, indicating that DMN analysis of PCC connectivity could represent a promising biomarker for early AD diagnosis (Sheline et al., 2010b; Sheline and Raichle, 2013). "
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    ABSTRACT: The default mode network (DMN) is a group of anatomically separate regions in the brain found to have synchronized patterns of activation in functional magnetic resonance imaging (fMRI). Mentation associated with the DMN includes processes such as mind wandering, autobiographical memory, self-reflective thought, envisioning the future, and considering the perspective of others. Abnormalities in the DMN have been linked to symptom severity in a variety of mental disorders indicating that the DMN could be used as a biomarker for diagnosis. These correlations have also led to the use of DMN modulation as a biomarker for assessing pharmacological treatments. Concurrent research investigating the neurocorrelates of meditation have associated DMN modulation with practice. Furthermore, meditative practice is increasingly understood to have a beneficial role in the treatment of mental disorders. Therefore we propose the use of DMN measures as a biomarker for monitoring the therapeutic effects of meditation practices in mental disorders. Recent findings support this perspective, and indicate the utility of DMN monitoring in understanding and developing meditative treatments for these debilitating conditions.
    Frontiers in Psychology 06/2015; 06. DOI:10.3389/fpsyg.2015.00776 · 2.80 Impact Factor
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    • "This pattern was consistent with that in previous studies which showed high ReHo (Long et al., 2008), ALFF and fALFF (Zang et al., 2007; Zou et al., 2008; Zuo et al., 2010) within the DMN. Previous studies have consistently demonstrated that the DMN regions show task-independent deactivation across a wide range of cognitive tasks compared with the resting-state (Shulman et al., 1997; Binder et al., 1999; Mazoyer et al., 2001), and these areas had signifi cantly higher blood fl ow and oxygen consumption than the global mean value (Raichle et al., 2001). The current results that DMN showed high activity is consistent with the conclusion that these regions represent the functional core underlying resting brain dynamics (Ghosh et al., 2008; Honey et al., 2009; Zuo et al., 2010). "
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