Cortical Hubs Revealed by Intrinsic Functional Connectivity: Mapping, Assessment of Stability, and Relation to Alzheimer's Disease

Department of Psychology and Center for Brain Science, Harvard University, Cambridge, Massachusetts 02138, USA.
The Journal of Neuroscience : The Official Journal of the Society for Neuroscience (Impact Factor: 6.75). 03/2009; 29(6):1860-73. DOI: 10.1523/JNEUROSCI.5062-08.2009
Source: PubMed

ABSTRACT Recent evidence suggests that some brain areas act as hubs interconnecting distinct, functionally specialized systems. These nexuses are intriguing because of their potential role in integration and also because they may augment metabolic cascades relevant to brain disease. To identify regions of high connectivity in the human cerebral cortex, we applied a computationally efficient approach to map the degree of intrinsic functional connectivity across the brain. Analysis of two separate functional magnetic resonance imaging datasets (each n = 24) demonstrated hubs throughout heteromodal areas of association cortex. Prominent hubs were located within posterior cingulate, lateral temporal, lateral parietal, and medial/lateral prefrontal cortices. Network analysis revealed that many, but not all, hubs were located within regions previously implicated as components of the default network. A third dataset (n = 12) demonstrated that the locations of hubs were present across passive and active task states, suggesting that they reflect a stable property of cortical network architecture. To obtain an accurate reference map, data were combined across 127 participants to yield a consensus estimate of cortical hubs. Using this consensus estimate, we explored whether the topography of hubs could explain the pattern of vulnerability in Alzheimer's disease (AD) because some models suggest that regions of high activity and metabolism accelerate pathology. Positron emission tomography amyloid imaging in AD (n = 10) compared with older controls (n = 29) showed high amyloid-beta deposition in the locations of cortical hubs consistent with the possibility that hubs, while acting as critical way stations for information processing, may also augment the underlying pathological cascade in AD.

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Available from: Jorge Sepulcre, Aug 25, 2015
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    • "ctures . This finding is generally robust against the spatial resolutions ( voxel - or region - level ) and centrality measures ( degree , efficiency or betweenness ) used , particularly for the posterior parietal regions . These identified hubs are comparable with previous structural and functional brain network studies ( Hagmann et al . , 2008 ; Buckner et al . , 2009 ; Gong et al . , 2009 ; Tomasi and Volkow , 2010 ; Liang et al . , 2013 ) . Moreover , the hub topography was independent of several factors of network type , network connectivity member and thresholding procedure , indicating that hubs are a stable , intrinsic property of brain network architecture . Of note , despite high spatial corre"
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    • "Nevertheless, brain connectivity shows dynamic variations in regions with a key role in task processing (Buckner et al., 2009). Accordingly, Buckner et al. (2009) compared high centrality brain regions between a task-free condition and a semantic categorization task. While the overall topography of such regions was similar between task-free and task-based conditions, regions in the prefrontal and temporal cortex showed an increased degree centrality in the semantic categorization task. "
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