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On the existence of a generalized non-specific task-dependent network.

Hugdahl K, Raichle ME, Mitra A, Specht K - Front Hum Neurosci (2015)

Bottom Line: We now suggest that this is because the brain utilizes the EMN network as a generalized response to tasks that exceeds a cognitive demand threshold and/or requires the processing of novel information.We further discuss how the EMN is related to the DMN, and how a network for extrinsic activity is related to a network for intrinsic activity.Finally, we discuss whether the EMN and DMN networks interact in a common single brain system, rather than being two separate and independent brain systems.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological and Medical Psychology, University of Bergen Bergen, Norway ; Division of Psychiatry, Haukeland University Hospital, Bergen Norway ; Department of Radiology, Haukeland University Hospital, Bergen Norway ; NORMENT Center of Excellence, University of Bergen Bergen, Norway.

ABSTRACT
In this paper we suggest the existence of a generalized task-related cortical network that is up-regulated whenever the task to be performed requires the allocation of generalized non-specific cognitive resources, independent of the specifics of the task to be performed. We have labeled this general purpose network, the extrinsic mode network (EMN) as complementary to the default mode network (DMN), such that the EMN is down-regulated during periods of task-absence, when the DMN is up-regulated, and vice versa. We conceptualize the EMN as a cortical network for extrinsic neuronal activity, similar to the DMN as being a cortical network for intrinsic neuronal activity. The EMN has essentially a fronto-temporo-parietal spatial distribution, including the inferior and middle frontal gyri, inferior parietal lobule, supplementary motor area, inferior temporal gyrus. We hypothesize that this network is always active regardless of the cognitive task being performed. We further suggest that failure of network up- and down-regulation dynamics may provide neuronal underpinnings for cognitive impairments seen in many mental disorders, such as, e.g., schizophrenia. We start by describing a common observation in functional imaging, the close overlap in fronto-parietal activations in healthy individuals to tasks that denote very different cognitive processes. We now suggest that this is because the brain utilizes the EMN network as a generalized response to tasks that exceeds a cognitive demand threshold and/or requires the processing of novel information. We further discuss how the EMN is related to the DMN, and how a network for extrinsic activity is related to a network for intrinsic activity. Finally, we discuss whether the EMN and DMN networks interact in a common single brain system, rather than being two separate and independent brain systems.

No MeSH data available.


Related in: MedlinePlus

The figure displays the probability maps for significant activations and deactivations across the nine studies shown in Figure 1. Each study was binarized at a threshold of p < 0.001 and voxel-wise summed up. Thus, the displayed voxels reflect the probability (in %) that they were found to be activated (red) or deactivated (blue) by the nine studies shown in Figure 1. The red areas mainly reflect the EMN (see also Figure 2), while the blue areas correspond to the core areas of the DMN.
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Figure 3: The figure displays the probability maps for significant activations and deactivations across the nine studies shown in Figure 1. Each study was binarized at a threshold of p < 0.001 and voxel-wise summed up. Thus, the displayed voxels reflect the probability (in %) that they were found to be activated (red) or deactivated (blue) by the nine studies shown in Figure 1. The red areas mainly reflect the EMN (see also Figure 2), while the blue areas correspond to the core areas of the DMN.

Mentions: Table 2 shows further details about the jointly activated areas in the conjunctions analysis, including hemisphere side, Brodmann area, x,y,z MNI co-ordinates, cluster voxel size, and threshold z-values. Figure 3 shows statistical probability maps for % overlap for activated and de-activated areas across the nine Bergen studies. As can be seen in Figure 3, areas that are de-activated across the nine studies overlap with areas being active in the classic default mode network (DMN; Raichle et al., 2001), including ventromedial inferior frontal, posterior cingulate, parietal/precuneus areas. Thus, the probability maps seen in Figure 3 reveal a negative relationship between the suggested generalized task-driven network and the DMN, such that activated and deactivated areas have non-overlapping spatial distributions.


On the existence of a generalized non-specific task-dependent network.

Hugdahl K, Raichle ME, Mitra A, Specht K - Front Hum Neurosci (2015)

The figure displays the probability maps for significant activations and deactivations across the nine studies shown in Figure 1. Each study was binarized at a threshold of p < 0.001 and voxel-wise summed up. Thus, the displayed voxels reflect the probability (in %) that they were found to be activated (red) or deactivated (blue) by the nine studies shown in Figure 1. The red areas mainly reflect the EMN (see also Figure 2), while the blue areas correspond to the core areas of the DMN.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4526816&req=5

Figure 3: The figure displays the probability maps for significant activations and deactivations across the nine studies shown in Figure 1. Each study was binarized at a threshold of p < 0.001 and voxel-wise summed up. Thus, the displayed voxels reflect the probability (in %) that they were found to be activated (red) or deactivated (blue) by the nine studies shown in Figure 1. The red areas mainly reflect the EMN (see also Figure 2), while the blue areas correspond to the core areas of the DMN.
Mentions: Table 2 shows further details about the jointly activated areas in the conjunctions analysis, including hemisphere side, Brodmann area, x,y,z MNI co-ordinates, cluster voxel size, and threshold z-values. Figure 3 shows statistical probability maps for % overlap for activated and de-activated areas across the nine Bergen studies. As can be seen in Figure 3, areas that are de-activated across the nine studies overlap with areas being active in the classic default mode network (DMN; Raichle et al., 2001), including ventromedial inferior frontal, posterior cingulate, parietal/precuneus areas. Thus, the probability maps seen in Figure 3 reveal a negative relationship between the suggested generalized task-driven network and the DMN, such that activated and deactivated areas have non-overlapping spatial distributions.

Bottom Line: We now suggest that this is because the brain utilizes the EMN network as a generalized response to tasks that exceeds a cognitive demand threshold and/or requires the processing of novel information.We further discuss how the EMN is related to the DMN, and how a network for extrinsic activity is related to a network for intrinsic activity.Finally, we discuss whether the EMN and DMN networks interact in a common single brain system, rather than being two separate and independent brain systems.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological and Medical Psychology, University of Bergen Bergen, Norway ; Division of Psychiatry, Haukeland University Hospital, Bergen Norway ; Department of Radiology, Haukeland University Hospital, Bergen Norway ; NORMENT Center of Excellence, University of Bergen Bergen, Norway.

ABSTRACT
In this paper we suggest the existence of a generalized task-related cortical network that is up-regulated whenever the task to be performed requires the allocation of generalized non-specific cognitive resources, independent of the specifics of the task to be performed. We have labeled this general purpose network, the extrinsic mode network (EMN) as complementary to the default mode network (DMN), such that the EMN is down-regulated during periods of task-absence, when the DMN is up-regulated, and vice versa. We conceptualize the EMN as a cortical network for extrinsic neuronal activity, similar to the DMN as being a cortical network for intrinsic neuronal activity. The EMN has essentially a fronto-temporo-parietal spatial distribution, including the inferior and middle frontal gyri, inferior parietal lobule, supplementary motor area, inferior temporal gyrus. We hypothesize that this network is always active regardless of the cognitive task being performed. We further suggest that failure of network up- and down-regulation dynamics may provide neuronal underpinnings for cognitive impairments seen in many mental disorders, such as, e.g., schizophrenia. We start by describing a common observation in functional imaging, the close overlap in fronto-parietal activations in healthy individuals to tasks that denote very different cognitive processes. We now suggest that this is because the brain utilizes the EMN network as a generalized response to tasks that exceeds a cognitive demand threshold and/or requires the processing of novel information. We further discuss how the EMN is related to the DMN, and how a network for extrinsic activity is related to a network for intrinsic activity. Finally, we discuss whether the EMN and DMN networks interact in a common single brain system, rather than being two separate and independent brain systems.

No MeSH data available.


Related in: MedlinePlus