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@PHDTHESIS{Stumme:910366,
      author       = {Stumme, Johanna},
      title        = {{F}unctional network reorganization in older adults :
                      structural relations and its impact on sex and cognitive
                      performance},
      school       = {RWTH Aachen},
      type         = {Dissertation},
      publisher    = {RWTH Aachen University},
      reportid     = {FZJ-2022-03777},
      pages        = {pages 1 Online-Ressource : Illustrationen},
      year         = {2022},
      note         = {Dissertation, RWTH Aachen, 2022},
      abstract     = {The normal aging process is accompanied by a progressive
                      decrease of cognitive abilities which is highly variable
                      across individuals. Sources of heterogeneity are far from
                      being fully understood, but seem to be associated with
                      multiple neurobiological substrates. The present work aimed
                      at contributing to this highly important issue of
                      identifying potential neurobiological sources for the
                      inter-individual variability in higher age. Therefore, the
                      whole brain’s resting-state functional connectivity
                      (RSFC), its association with age, sex, cognitive performance
                      as well as its relation to structural connectivity (SC) was
                      investigated. The first studies’ results based on 772
                      older adults (55-87 years) indicate aging to be accompanied
                      by a shift from rather specialized and segregated functional
                      networks towards a higher network integration. These results
                      not only underpin previous findings based on lifespan
                      samples, but additionally expand the current state of
                      research by showing that this trend also persists into older
                      age. Moreover, as compared to lifespan studies, different
                      networks were found to be affected in older adults: While
                      predominantly higher-order networks change across the
                      lifespan, in older adults particularly the primary
                      processing networks seem to be age sensitive. Furthermore,
                      they were found to influence the cognitive performance
                      differences in aging, i.e. lower RSFC of the visual and
                      sensorimotor network (SMN) being associated with lower
                      cognitive performance. With regards to sex, RSFC differences
                      were found between males and females, potentially
                      facilitating sex-related behavioral functioning and
                      emphasizing the need for sex-stratified analyses in studies
                      with older subjects. Building upon the results of the first
                      study, the second study aimed at unveiling potential origins
                      for the depicted RSFC differences by relating age-related
                      RSFC differences to SC differences (n=636, 55-85 years).
                      Although SC is the underlying construct for brain regions to
                      exchange information, RSFC cannot yet be directly linked to
                      SC. Using a multivariate statistical approach, whole-brain
                      region-wise RSFC and SC estimates were used to predict the
                      older adults age and to thereby unveil RSFC and SC
                      differences that are together age-characteristic. Results
                      indicate that while for RSFC regions of the SMN are
                      particularly indicative for older peoples’ chronological
                      age to, SC of the frontal lobes seems be age-characteristic.
                      Additionally, the results point at two differential age
                      progressions: If age-related differences in SC only affect
                      the frontal lobe, RSFC of the SMN is relatively preserved.
                      In contrast, if age-related decreases in SC pertain to the
                      whole brain, the SMN shows overall RSFC decreases, which
                      with regards to results of the first study potentially hint
                      at a more accelerated aging process. In conclusion, the
                      age-related RSFC reorganization in older adults particularly
                      affects the SMN. Here, differences are not only related to
                      cognitive performance decline, but also dependent on
                      whole-brain SC differences underpinning the necessity to
                      integrate multiple modalities for a comprehensive
                      understanding of the cognitive aging in older adults.},
      keywords     = {aging , cognitive performance , functional connectivity ,
                      structural connectivity , Alterungsprozess , kognitive
                      Leistung , funktionelle Konnektivität , strukturelle
                      Konnektivität (Other)},
      cin          = {INM-1},
      cid          = {I:(DE-Juel1)INM-1-20090406},
      pnm          = {5251 - Multilevel Brain Organization and Variability
                      (POF4-525)},
      pid          = {G:(DE-HGF)POF4-5251},
      typ          = {PUB:(DE-HGF)11},
      doi          = {10.18154/RWTH-2022-03308},
      url          = {https://juser.fz-juelich.de/record/910366},
}