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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

Resulting joint activations after conjunction analysis of the nine different studies shown in Figure 1.
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Figure 2: Resulting joint activations after conjunction analysis of the nine different studies shown in Figure 1.

Mentions: To further probe the commonalities of activations across task and cognitive processes, we performed a conjunction analysis across studies and data sets. The conjunction analysis was done by converting the spmT maps from the nine respective studies into Z-maps that are independent from degrees of freedom. Inclusive conjunction was estimated as a global conjunction analysis and thus based on a minimal Z-value statistics and a cumulative p-value of p < 0.0001 was applied, corresponding to a threshold for the single studies as the ninth root of 0.0001. The result is seen in Figure 2 and supports the findings shown in Figure 1 from observing the different activations across studies when they are displayed together.


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

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

Resulting joint activations after conjunction analysis of the nine different studies shown in Figure 1.
© Copyright Policy
Related In: Results  -  Collection

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

Figure 2: Resulting joint activations after conjunction analysis of the nine different studies shown in Figure 1.
Mentions: To further probe the commonalities of activations across task and cognitive processes, we performed a conjunction analysis across studies and data sets. The conjunction analysis was done by converting the spmT maps from the nine respective studies into Z-maps that are independent from degrees of freedom. Inclusive conjunction was estimated as a global conjunction analysis and thus based on a minimal Z-value statistics and a cumulative p-value of p < 0.0001 was applied, corresponding to a threshold for the single studies as the ninth root of 0.0001. The result is seen in Figure 2 and supports the findings shown in Figure 1 from observing the different activations across studies when they are displayed together.

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