Integrating Temporal and Spatial Scales: Human Structural Network Motifs Across Age and Region of Interest Size

“…Because small parcel-size variation across different samples (instances of a random parcellation) is critical to ensure comparable network metrics across several parcellation trials, we propose a random parcellation algorithm that can produce sets of random parcellations with a given number of parcels with a small parcel-size variability. The inter-quartile range to median ratio is around 0.10, significantly smaller than previous results: 0.77 ( Smith et al, 2004 ) and 0.52 ( Echtermeyer et al, 2011 ). Another advantage of this algorithm is that it generates the number of nodes exactly as specified.…”

“…Table 1 summarizes some features of the distributions obtained for different values of N . The inter-quartile range to median ratio is 10% for 500 parcels and 12% for 1000 parcels, much smaller compared to previous reported values of random parcellation with 0.77 for 890 parcels ( Fornito et al, 2010 ) and 0.52 for 813 parcels ( Echtermeyer et al, 2011 ).…”

“…According to our analysis, the highly robust topological encapsulation of these predominantly lateral modules against the applied spatially constrained rewiring indicates that their existence can largely be explained by cortical wiring constraints. Additionally, however, the natural emergence of these module formations may enable them to provide a consistent base or ‘backbone’ to the cortex's modular structure both across individual variation and through development and ageing processes [24] . Such a modular ‘backbone’ structure could provide the structural basis for some relatively invariant, recurring components of the continuously reconfiguring functional networks of the brain [77] .…”

“…In the future, we would further study those different networks. Moreover, we may perform this analysis for different parcellation schemes as node definition can affect network properties 36 40 41 42 43 . We could also perform the analysis for patients with other cognitive impairment such as mild cognitive impairment, frontotemporal dementia and dementia with Lewy bodies.…”