Rich Club Hubs

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Chapter 6 endnote 20, from How Emotions are Made: The Secret Life of the Brain by Lisa Feldman Barrett.
Some context is:

...information can pass efficiently between different networks in your brain via the major hubs in the interoceptive and control networks. [...] This efficient structure is a small world architecture with rich club hubs.

A group of densely interconnected neurons is called a "node".  Certain nodes have special properties — when they are densely connected, they are called "hubs."[1][2][3] Certain hubs are said to be members of the "rich club" because they are densely interconnected with one another, and are more densely connected to other brain regions than those regions are with one another.[4] The human brain's small world architecture, within networks that overlap in rich club hubs,[5] makes sense from an evolutionary standpoint. Natural selection should favor a brain organization that is efficient for information flow but that isn’t too costly to support. The small world architecture with rich clubs fits these criteria.[6]

All intrinsic networks contain hubs of the rich club, creating a high-capacity backbone for synchronizing brain activity across networks.[7] The majority of rich club hubs can be found in the interoceptive and control networks: 37% of rich club hubs are contained within the "default mode" portion of the interoceptive network, 30% in the "salience" portion of the interoceptive network, and 22% in the control network (compared to between 5 and 15% of the sensory and motor networks; average 11%).[5] As a consequence, the mutual connectivity between the default mode, salience, and frontoparietal networks is seven times higher than connectivity between the other networks, indicating that these networks are central to the anatomical infrastructure that integrates information across the brain.  The hubs of the rich club account for 76% of all connectivity between these core networks (i.e., the interoceptive and control networks) and the sensory and motor networks.

Rich club hubs also differ in the cytoarchitectural organization in ways that make them well-suited for information synthesis.[8][9]

Notes on the Notes

  1. Sporns, Olaf. 2011. Networks of the Brain. Cambridge, MA: MIT Press.
  2. Also called the "structural core"; see Sepulcre, Jorge, Mert R. Sabuncu, Thomas B. Yeo, Hesheng Liu, and Keith A. Johnson. 2012. "Stepwise connectivity of the modal cortex reveals the multimodal organization of the human brain." The Journal of Neuroscience 32 (31): 10649-10661.
  3. Buckner, Randy L., Jorge Sepulcre, Tanveer Talukdar, Fenna M. Krienen, Hesheng Liu, Trey Hedden, Jessica R. Andrews-Hanna, Reisa A. Sperling, and Keith A. Johnson. 2009. "Cortical hubs revealed by intrinsic functional connectivity: mapping, assessment of stability, and relation to Alzheimer's disease." Journal of Neuroscience 29 (6): 1860-1873.
  4. Van Den Heuvel, Martijn P., and Olaf Sporns. 2011. "Rich-club organization of the human connectome." Journal of Neuroscience 31 (44): 15775-15786.
  5. 5.0 5.1 Van den Heuvel, Martijn P., and Olaf Sporns. 2013. “An Anatomical Substrate for Integration Among Functional Networks in Human Cortex.” Journal of Neuroscience 33 (36): 14489–14500.
  6. Bullmore & Sporns, 2013
  7. Van den Heuvel, Martijn P., René S. Kahn, Joaquín Goñi, and Olaf Sporns. 2012. "High-cost, high-capacity backbone for global brain communication." Proceedings of the National Academy of Sciences 109 (28): 11372-11377.    
  8. Scholtens, Lianne H., Ruben Schmidt, Marcel A. de Reus, and Martijn P. van den Heuvel. 2014. "Linking macroscale graph analytical organization to microscale neuroarchitectonics in the macaque connectome." Journal of Neuroscience 34 (36): 12192-12205.
  9. Van den Heuvel, Martijn P., Lianne H. Scholtens, Elise Turk, Dante Mantini, Wim Vanduffel, and Lisa Feldman Barrett. 2016. "Multimodal analysis of cortical chemoarchitecture and macroscale fMRI resting‐state functional connectivity." Human Brain Mapping 37 (9): 3103-3113.