title: Connectivity trajectory across lifespan differentiates the precuneus from the default network.
abstract: The default network of the human brain has drawn much attention due to its relevance to various brain disorders, cognition, and behavior. However, its functional components and boundaries have not been precisely defined. There is no consensus as to whether the precuneus, a hub in the functional connectome, acts as part of the default network. This discrepancy is more critical for brain development and aging studies: it is not clear whether age has a stronger impact on the default network or precuneus, or both. We used Generalized Ranking and Averaging Independent Component Analysis by Reproducibility (gRAICAR) to investigate the lifespan trajectories of intrinsic functional networks. By estimating individual-specific spatial components and aligning them across subjects, gRAICAR measures the spatial variation of component maps across a population without constraining the same components to appear in every subject. In a cross-lifespan fMRI dataset (N=126, 7-85years old), we observed stronger age dependence in the spatial pattern of a precuneus-dorsal posterior cingulate cortex network compared to the default network, despite the fact that the two networks exhibit considerable spatial overlap and temporal correlation. These results remained even when analyses were restricted to a subpopulation with very similar head motion across age. Our analyses further showed that the two networks tend to merge with increasing age. Post-hoc analyses of functional connectivity confirmed the distinguishable cross-lifespan trajectories between the two networks. Based on these observations, we proposed a dynamic model of cross-lifespan functional segregation and integration between the two networks, suggesting that the precuneus network may have a different functional role than the default network, which declines with age. These findings have implications for understanding the functional roles of the default network, gaining insight into its dynamics throughout life, and guiding interpretation of alterations in brain disorders.
authors.affiliation: Key Laboratory of Behavioral Science, Laboratory for Functional Connectome and Development, Magnetic Resonance Imaging Research Center, Institute of Psychology, Chinese Academy of Sciences, Beijing 100101, China; Section on Functional Imaging Methods, Laboratory of Brain and Cognition, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA. Electronic address: yangz@psych.ac.cn.
authors.forename: Zhi
authors.initials: Z
authors.lastname: Yang
authors.affiliation: Advanced MRI Section, Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Catie
authors.initials: C
authors.lastname: Chang
authors.affiliation: Key Laboratory of Behavioral Science, Laboratory for Functional Connectome and Development, Magnetic Resonance Imaging Research Center, Institute of Psychology, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Ting
authors.initials: T
authors.lastname: Xu
authors.affiliation: Key Laboratory of Behavioral Science, Laboratory for Functional Connectome and Development, Magnetic Resonance Imaging Research Center, Institute of Psychology, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Lili
authors.initials: L
authors.lastname: Jiang
authors.affiliation: Section on Functional Imaging Methods, Laboratory of Brain and Cognition, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Handwerker
authors.affiliation: Nathan Kline Institute for Psychiatric Research, Orangeburg, NY 10962, USA; Center for Neurodevelopmental Disorders, New York University Langone Medical Center Child Study Center, New York, NY 10016, USA.
authors.forename: F Xavier
authors.initials: FX
authors.lastname: Castellanos
authors.affiliation: Nathan Kline Institute for Psychiatric Research, Orangeburg, NY 10962, USA; Center for the Developing Brain, Child Mind Institute, New York, NY 10022, USA.
authors.forename: Michael P
authors.initials: MP
authors.lastname: Milham
authors.affiliation: Section on Functional Imaging Methods, Laboratory of Brain and Cognition, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Peter A
authors.initials: PA
authors.lastname: Bandettini
authors.affiliation: Key Laboratory of Behavioral Science, Laboratory for Functional Connectome and Development, Magnetic Resonance Imaging Research Center, Institute of Psychology, Chinese Academy of Sciences, Beijing 100101, China. Electronic address: zuoxn@psych.ac.cn.
authors.forename: Xi-Nian
authors.initials: XN
authors.lastname: Zuo
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D001921:Brain / Q000502:physiology*; D002648:Child; D063132:Connectome; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009415:Nerve Net / Q000502:physiology*; D010296:Parietal Lobe / Q000502:physiology*; D055815:Young Adult
keywords: Default network; Functional connectome; Independent component analysis; Lifespan trajectory; Precuneus; gRAICAR