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Hum Brain Mapp. 2017 Jul;38(7):3659-3674. doi: 10.1002/hbm.23621. Epub 2017 Apr 22.

Transition of the functional brain network related to increasing cognitive demands.

Author information

1
Centre for Modern Interdisciplinary Technologies, Nicolaus Copernicus University, Toruń, Poland.
2
Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Toruń, Poland.
3
Bioimaging Research Center, World Hearing Center of Institute of Physiology and Pathology of Hearing, Warsaw/Kajetany, Poland.
4
Faculty of Humanities, Nicolaus Copernicus University, Toruń, Poland.
5
Center for Lifespan Psychology, Max Planck Institute for Human Development, Berlin, Germany.
6
Department of Psychiatry and Psychotherapy, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.

Abstract

Network neuroscience provides tools that can easily be used to verify main assumptions of the global workspace theory (GWT), such as the existence of highly segregated information processing during effortless tasks performance, engagement of multiple distributed networks during effortful tasks and the critical role of long-range connections in workspace formation. A number of studies support the assumptions of GWT by showing the reorganization of the whole-brain functional network during cognitive task performance; however, the involvement of specific large scale networks in the formation of workspace is still not well-understood. The aims of our study were: (1) to examine changes in the whole-brain functional network under increased cognitive demands of working memory during an n-back task, and their relationship with behavioral outcomes; and (2) to provide a comprehensive description of local changes that may be involved in the formation of the global workspace, using hub detection and network-based statistic. Our results show that network modularity decreased with increasing cognitive demands, and this change allowed us to predict behavioral performance. The number of connector hubs increased, whereas the number of provincial hubs decreased when the task became more demanding. We also found that the default mode network (DMN) increased its connectivity to other networks while decreasing connectivity between its own regions. These results, apart from replicating previous findings, provide a valuable insight into the mechanisms of the formation of the global workspace, highlighting the role of the DMN in the processes of network integration. Hum Brain Mapp 38:3659-3674, 2017.

KEYWORDS:

default mode network; fMRI; functional connectivity; global workspace theory; graph theory; modularity; n-back; network-based statistic; working memory

PMID:
28432773
DOI:
10.1002/hbm.23621

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