Subcortical Anatomy of the Default Mode Network: a functional and structural connectivity study

AbstractMost existing research into the default-mode network (DMN) has taken a corticocentric approach. Despite the resemblance of the DMN with the unitary model of the limbic system, the anatomy and contribution of subcortical structures to the network may be underappreciated due to methods limitation. Here, we propose a new and more comprehensive neuroanatomical model of the DMN including the basal forebrain and anterior and mediodorsal thalamic nuclei and cholinergic nuclei. This has been achieved by considering functional territories during interindividual brain alignment. Additionally, tractography of diffusion-weighted imaging was employed to explore the structural connectivity of the DMN and revealed that the thalamus and basal forebrain had high importance in term of values of node degree and centrality in the network. The contribution of these neurochemically diverse brain nuclei reconciles previous neuroimaging with neuropathological findings in diseased brain and offers the potential for identifying a conserved homologue of the DMN in other mammalian species.

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An improved neuroanatomical model of the default-mode network reconciles previous neuroimaging and neuropathological findings

Communications Biology ◽

10.1038/s42003-019-0611-3 ◽

2019 ◽

Vol 2 (1) ◽

Cited By ~ 27

Author(s):

Pedro Nascimento Alves ◽

Chris Foulon ◽

Vyacheslav Karolis ◽

Danilo Bzdok ◽

Daniel S. Margulies ◽

...

Keyword(s):

Default Mode Network ◽

Basal Forebrain ◽

Mammalian Species ◽

Structural Connectivity ◽

Thalamic Nuclei ◽

Subcortical Structures ◽

Default Mode ◽

Multiple Networks ◽

Unitary Model ◽

The Brain

Abstract The brain is constituted of multiple networks of functionally correlated brain areas, out of which the default-mode network (DMN) is the largest. Most existing research into the DMN has taken a corticocentric approach. Despite its resemblance with the unitary model of the limbic system, the contribution of subcortical structures to the DMN may be underappreciated. Here, we propose a more comprehensive neuroanatomical model of the DMN including subcortical structures such as the basal forebrain, cholinergic nuclei, anterior and mediodorsal thalamic nuclei. Additionally, tractography of diffusion-weighted imaging was employed to explore the structural connectivity, which revealed that the thalamus and basal forebrain are of central importance for the functioning of the DMN. The contribution of these neurochemically diverse brain nuclei reconciles previous neuroimaging with neuropathological findings in diseased brains and offers the potential for identifying a conserved homologue of the DMN in other mammalian species.

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Increased posterior default mode network activity and structural connectivity in young adult APOE-ε4 carriers: a multimodal imaging investigation

Neurobiology of Aging ◽

10.1016/j.neurobiolaging.2018.08.026 ◽

2019 ◽

Vol 73 ◽

pp. 82-91 ◽

Cited By ~ 10

Author(s):

Carl J. Hodgetts ◽

Jonathan P. Shine ◽

Huw Williams ◽

Mark Postans ◽

Rebecca Sims ◽

...

Keyword(s):

Young Adult ◽

Default Mode Network ◽

Multimodal Imaging ◽

Structural Connectivity ◽

Network Activity ◽

Default Mode ◽

Apoe Ε4

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Basal forebrain contributes to default mode network regulation

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1712431115 ◽

2018 ◽

Vol 115 (6) ◽

pp. 1352-1357 ◽

Cited By ~ 19

Author(s):

Jayakrishnan Nair ◽

Arndt-Lukas Klaassen ◽

Jozsef Arato ◽

Alexei L. Vyssotski ◽

Michael Harvey ◽

...

Keyword(s):

Default Mode Network ◽

Basal Forebrain ◽

Cognitive Task ◽

Gamma Oscillations ◽

Anterior Cingulate ◽

Gamma Activity ◽

Sensory Stimuli ◽

Quiet Wakefulness ◽

Default Mode ◽

Brain States

The default mode network (DMN) is a collection of cortical brain regions that is active during states of rest or quiet wakefulness in humans and other mammalian species. A pertinent characteristic of the DMN is a suppression of local field potential gamma activity during cognitive task performance as well as during engagement with external sensory stimuli. Conversely, gamma activity is elevated in the DMN during rest. Here, we document that the rat basal forebrain (BF) exhibits the same pattern of responses, namely pronounced gamma oscillations during quiet wakefulness in the home cage and suppression of this activity during active exploration of an unfamiliar environment. We show that gamma oscillations are localized to the BF and that gamma-band activity in the BF has a directional influence on a hub of the rat DMN, the anterior cingulate cortex, during DMN-dominated brain states. The BF is well known as an ascending, activating, neuromodulatory system involved in wake–sleep regulation, memory formation, and regulation of sensory information processing. Our findings suggest a hitherto undocumented role of the BF as a subcortical node of the DMN, which we speculate may be important for switching between internally and externally directed brain states. We discuss potential BF projection circuits that could underlie its role in DMN regulation and highlight that certain BF nuclei may provide potential target regions for up- or down-regulation of DMN activity that might prove useful for treatment of DMN dysfunction in conditions such as epilepsy or major depressive disorder.

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Characterization of Structural Connectivity of the Default Mode Network in Dogs using Diffusion Tensor Imaging

Scientific Reports ◽

10.1038/srep36851 ◽

2016 ◽

Vol 6 (1) ◽

Cited By ~ 6

Author(s):

Jennifer L. Robinson ◽

Madhura Baxi ◽

Jeffrey S. Katz ◽

Paul Waggoner ◽

Ronald Beyers ◽

...

Keyword(s):

Diffusion Tensor Imaging ◽

Default Mode Network ◽

Diffusion Tensor ◽

Structural Connectivity ◽

Default Mode

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Default mode network functional and structural connectivity after traumatic brain injury

Brain ◽

10.1093/brain/awr175 ◽

2011 ◽

Vol 134 (8) ◽

pp. 2233-2247 ◽

Cited By ~ 247

Author(s):

David J. Sharp ◽

Christian F. Beckmann ◽

Richard Greenwood ◽

Kirsi M. Kinnunen ◽

Valerie Bonnelle ◽

...

Keyword(s):

Traumatic Brain Injury ◽

Brain Injury ◽

Default Mode Network ◽

Structural Connectivity ◽

Default Mode

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Resting-State Functional Connectivity Reflects Structural Connectivity in the Default Mode Network

Cerebral Cortex ◽

10.1093/cercor/bhn059 ◽

2008 ◽

Vol 19 (1) ◽

pp. 72-78 ◽

Cited By ~ 1360

Author(s):

M. D. Greicius ◽

K. Supekar ◽

V. Menon ◽

R. F. Dougherty

Keyword(s):

Functional Connectivity ◽

Default Mode Network ◽

Resting State ◽

Structural Connectivity ◽

Resting State Functional Connectivity ◽

Default Mode

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Development of functional and structural connectivity within the default mode network in young children

NeuroImage ◽

10.1016/j.neuroimage.2010.04.009 ◽

2010 ◽

Vol 52 (1) ◽

pp. 290-301 ◽

Cited By ~ 330

Author(s):

Kaustubh Supekar ◽

Lucina Q. Uddin ◽

Katherine Prater ◽

Hitha Amin ◽

Michael D. Greicius ◽

...

Keyword(s):

Young Children ◽

Default Mode Network ◽

Structural Connectivity ◽

Default Mode

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Altered Inter-Subregion Connectivity of the Default Mode Network in Relapsing Remitting Multiple Sclerosis: A Functional and Structural Connectivity Study

PLoS ONE ◽

10.1371/journal.pone.0101198 ◽

2014 ◽

Vol 9 (7) ◽

pp. e101198 ◽

Cited By ~ 30

Author(s):

Fuqing Zhou ◽

Ying Zhuang ◽

Honghan Gong ◽

Bo Wang ◽

Xing Wang ◽

...

Keyword(s):

Multiple Sclerosis ◽

Default Mode Network ◽

Structural Connectivity ◽

Default Mode ◽

Relapsing Remitting ◽

Remitting Multiple Sclerosis ◽

Relapsing Remitting Multiple Sclerosis

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Increased posterior default mode network activity and structural connectivity in young adult APOE-ε4 carriers: a multi-modal imaging investigation

10.1101/285536 ◽

2018 ◽

Author(s):

Carl J. Hodgetts ◽

Jonathan P. Shine ◽

Huw Williams ◽

Mark Postans ◽

Rebecca Sims ◽

...

Keyword(s):

Young Adult ◽

Default Mode Network ◽

Medial Temporal Lobe ◽

Structural Connectivity ◽

Mean Diffusivity ◽

Network Activity ◽

Default Mode ◽

Cingulum Bundle ◽

Brain Changes ◽

Increased Activity

AbstractYoung adult APOE-ε4 carriers show increased activity in posterior regions of the default mode network (pDMN), but how this is related to structural connectivity is unknown. Thirty young adults (half APOE-ε4 carriers, the other half APOE-ε3ε3/ε2ε3; mean age 20 years) were scanned using both diffusion and functional magnetic resonance imaging. Diffusion tractography was used to quantify the microstructure (mean diffusivity, MD; fractional anisotropy, FA) of the parahippocampal cingulum bundle (PHCB), which links pDMN and the medial temporal lobe. APOE-ε4 carriers had lower MD and higher FA relative to non-carriers in PHCB. Further, PHCB microstructure was selectively associated with pDMN activity during a scene discrimination task known to be sensitive to Alzheimer’s disease (AD). These findings are consistent with a lifespan view of AD risk, where early-life structural and functional brain changes in specific, vulnerable networks leads to increased neural activity that may ultimately trigger amyloid-ß deposition.

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