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Chapter 13 endnote 3, from How Emotions are Made: The Secret Life of the Brain by Lisa Feldman Barrett.
Some context is:

Just as the arbor of a tree grows in the spring and shrinks in the fall, interconnections between your axons and dendrites increase and decrease as you age. You even grow new neurons in certain brain regions. This kind of anatomical change, called plasticity, also occurs with experience.

As you age, your brain networks continually trade off between cost and efficiency. For example, in childhood and adolescence, brain growth comes from myelination (the wrapping around axons), thickening of axons, and increased synaptic density.[1] When you’re an adolescent, you have fewer short-range and more long-range connections, promoting efficient processing.[1] More generally, modularity decreases, and integration increases, with age into adulthood.[1] These changes increase the metabolic cost of neural processing, because long-range connections are expensive,[2][3] with most of the energy costs going to signaling between neurons, particularly in post-synaptic processes.[4][5][6][7]

Intrinsic networks also appear and retreat at different ages. Preterm infants have five intrinsic networks, but the default mode network is not among them[8] (although the major connection between medial prefrontal cortex and posterior cingulate cortex is in place). The default mode network becomes more fully developed by one year of age in some studies,[9][10] and later in others.[11] As adults age and their cells lose some ability to divide and grow, a loss known as senescence, the default mode network has reduced connectivity,[12] and so do parts of the salience network (particularly the dorsal subnetwork).[13] Recall from the book that the salience and default mode networks together form the interoceptive network.[14]

Notes on the Notes

  1. 1.0 1.1 1.2 Hagmann, Patric, Olaf Sporns, Neel Madan, Leila Cammoun, Rudolph Pienaar, Van Jay Wedeen, Reto Meuli, J-P. Thiran, and P. E. Grant. 2010. "White matter maturation reshapes structural connectivity in the late developing human brain." Proceedings of the National Academy of Sciences 107 (44): 19067-19072
  2. Bullmore, Ed, and Olaf Sporns. 2012. "The economy of brain network organization." Nature Reviews Neuroscience 13 (5): 336-349.
  3. Sterling, Peter, and Simon Laughlin. 2015. Principles of Neural Design. Cambridge, MA: MIT Press.
  4. Attwell, David, and Simon B. Laughlin. 2001. "An energy budget for signaling in the grey matter of the brain." Journal of Cerebral Blood Flow & Metabolism 21 (10): 1133-1145.
  5. Attwell, David, and Costantino Iadecola. 2002. "The neural basis of functional brain imaging signals." Trends in Neurosciences 25 (12): 621-625.
  6. Alle, Henrik, Arnd Roth, and Jörg RP Geiger. 2009. "Energy-efficient action potentials in hippocampal mossy fibers." Science 325 (5946): 1405-1408.
  7. Harris et al 2012 [full reference to be provided]
  8. Frasson et al 2007 [full reference to be provided]
  9. Gao, Wei, Hongtu Zhu, Kelly S. Giovanello, J. Keith Smith, Dinggang Shen, John H. Gilmore, and Weili Lin. 2009. "Evidence on the emergence of the brain's default network from 2-week-old to 2-year-old healthy pediatric subjects." Proceedings of the National Academy of Sciences 106 (16): 6790-6795.
  10. Lin et al., 2008 [full reference to be provided]
  11. Fair, Damien A., Alexander L. Cohen, Nico UF Dosenbach, Jessica A. Church, Francis M. Miezin, Deanna M. Barch, Marcus E. Raichle, Steven E. Petersen, and Bradley L. Schlaggar. 2008. "The maturing architecture of the brain's default network." Proceedings of the National Academy of Sciences 105 (10): 4028-4032.
  12. Andrews-Hanna et al., 2007 [full reference to be provided]
  13. Touroutoglou, Alexandra, and Joseph M. Andreano, Jiahe Zhang, Bradford C. Dickerson and Lisa Feldman Barrett. Under review. "Dissociable effects of aging on salience subnetwork connectivity mediate age-related changes in executive function and affect."
  14. Kleckner, Ian, Jiahe Zhang, Alexandra Touroutoglou, Lorena Chanes, Chenjie Xia, W. Kyle Simmons, Karen Quigley, Bradford Dickerson, and Lisa Feldman Barrett. 2017. “Evidence for a Large-Scale Brain System Supporting Interoception in Humans.” Nature Human Behavior 1: 0069.