title: Functional heterogeneity in the default mode network edges.
abstract: The brain's default mode network (DMN) has attracted tremendous attention, but its topology still lacks a substantial and operative definition. At the same time, recent efforts based on coactivation analysis suggest significant involvement of concomitant activation as an origin of synchronous activity, which is the basis of the network detection. Therefore, to establish the biological significance of the intrinsic remote connectivity, understanding such co-occurrence networks may be crucial. This study shows the results of monitoring the network's signal variation during random transitions among two divergent tasks and rest epochs. The subset of the DMN nodes showed three distinct activity levels; it was simultaneously characterized by the lack of a transition response between blocks. Additional connectivity analysis revealed components covering the other DMN nodes showing overshooting in response to a transition that were still connected to the posterior cingulate cortices (PCC), but by different signal components. The overall finding of multiple connectivity modes in the DMN provides a relevant explanation about the two seemingly contradictory characteristics of the network, robustness and variation.
authors.affiliation: Human Brain Research Center, Kyoto University Graduate School of Medicine , Kyoto, Japan .
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Aso
authors.forename: Hidenao
authors.initials: H
authors.lastname: Fukuyama
mesh_terms: D000293:Adolescent; D000328:Adult; D001921:Brain / Q000502:physiology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009415:Nerve Net / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology; D011932:Reading; D055815:Young Adult
keywords: BOLD signal; default mode network; functional connectivity; independent component analysis; large-scale cortical networks; task-positive network