Abstract
Healthy aging is usually accompanied by changes in the functional modular organization of the human brain, which may result in the decline of cognition and underlying brain dysfunction. However, the relationship between age-related brain functional modular structure differences and cognition remain debatable. In this study, we investigated the age-associated differences of modules and hubs from young, middle and old age groups, using resting-state fMRI data from a large cross-sectional adulthood sample. We first divided the subjects into three age groups and constructed an individual-level network for each subject. Subsequently, a module-guided group-level network construction method was applied to form a weighted network for each group from which functional modules were detected. The intra- and inter-modular connectivities were observed negatively correlated with age. According to the detected modules, we found the number of connector hubs in the young group was more than middle-age and old group, while the quantity of provincial hubs in middle-age group was discovered more than other two groups. Further ROI-wise analysis shows that different hubs have distinct age-associated trajectories of intra- and inter-modular connections, which suggests the different types of topological role transitions in functional networks across age groups. Our results indicated an inverse association between functional segregation/integration with age, which demonstrated age-associated differences in communication effeciency. This study provides a new perspective and useful information to better understand the normal aging of brain networks.
Highlights
Population aging is a widespread worldwide phenomenon and has been one of the research hotspots in the neuroimaging field (Ferreira and Busatto, 2013)
According to the group-level network construction method introduced in section Construction of Brain Networks, a grouplevel network was generated for each age group
According to the detected modular structures of three groups, we find the age-associated differences of modules
Summary
Population aging is a widespread worldwide phenomenon and has been one of the research hotspots in the neuroimaging field (Ferreira and Busatto, 2013). Growing evidence indicates that age is related to the altered configuration of large-scale functional brain networks, which may have implications for cognitive performance (Onoda et al, 2012; Ng et al, 2016). A common finding among rs-fMRI studies has indicated that the human brain is functionally organized into an efficient network architecture (Sporns et al, 2005). Studies examining the topology of brain network have indicated several characteristics of an efficient architecture, including the modular architecture and a small number of highly connected hubs (Van Den Heuvel and Pol, 2010; Van den Heuvel and Sporns, 2013a). Previous studies have indicated that each module of functional networks is associated with specific cognitive/behavior function (Bertolero et al, 2015). Previous research has demonstrated that many hubs with numerous connections disappear while some specific age-associated hubs appear during aging (Simkó et al, 2009)
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