title: Multivariate dynamical modelling of structural change during development.
abstract: Here we introduce a multivariate framework for characterising longitudinal changes in structural MRI using dynamical systems. The general approach enables modelling changes of states in multiple imaging biomarkers typically observed during brain development, plasticity, ageing and degeneration, e.g. regional gray matter volume of multiple regions of interest (ROIs). Structural brain states follow intrinsic dynamics according to a linear system with additional inputs accounting for potential driving forces of brain development. In particular, the inputs to the system are specified to account for known or latent developmental growth/decline factors, e.g. due to effects of growth hormones, puberty, or sudden behavioural changes etc. Because effects of developmental factors might be region-specific, the sensitivity of each ROI to contributions of each factor is explicitly modelled. In addition to the external effects of developmental factors on regional change, the framework enables modelling and inference about directed (potentially reciprocal) interactions between brain regions, due to competition for space, or structural connectivity, and suchlike. This approach accounts for repeated measures in typical MRI studies of development and aging. Model inversion and posterior distributions are obtained using earlier established variational methods enabling Bayesian evidence-based comparisons between various models of structural change. Using this approach we demonstrate dynamic cortical changes during brain maturation between 6 and 22 years of age using a large openly available longitudinal paediatric dataset with 637 scans from 289 individuals. In particular, we model volumetric changes in 26 bilateral ROIs, which cover large portions of cortical and subcortical gray matter. We account for (1) puberty-related effects on gray matter regions; (2) effects of an early transient growth process with additional time-lag parameter; (3) sexual dimorphism by modelling parameter differences between boys and girls. There is evidence that the regional pattern of sensitivity to dynamic hidden growth factors in late childhood is similar across genders and shows a consistent anterior-posterior gradient with strongest impact to prefrontal cortex (PFC) brain changes. Finally, we demonstrate the potential of the framework to explore the coupling of structural changes across a priori defined subnetworks using an example of previously established resting state functional connectivity.
authors.affiliation: Institute of Cognitive Neurology and Dementia Research, Otto-von-Guericke-University Magdeburg, 39120 Magdeburg, Germany; German Center for Neurodegenerative Diseases (DZNE), 39120 Magdeburg, Germany. Electronic address: gabriel.ziegler@dzne.de.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Ziegler
authors.affiliation: FMRIB Centre, University of Oxford, Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, Headington, Oxford OX3 9DU, UK; Wellcome Trust Centre for Neuroimaging, University College, London WC1N 3BG, UK.
authors.forename: Gerard R
authors.initials: GR
authors.lastname: Ridgway
authors.affiliation: Institute of Cognitive Neuroscience, University College, London WC1N 3BG, UK.
authors.forename: Sarah-Jayne
authors.initials: SJ
authors.lastname: Blakemore
authors.affiliation: Wellcome Trust Centre for Neuroimaging, University College, London WC1N 3BG, UK.
authors.forename: John
authors.initials: J
authors.lastname: Ashburner
authors.affiliation: Wellcome Trust Centre for Neuroimaging, University College, London WC1N 3BG, UK.
authors.forename: Will
authors.initials: W
authors.lastname: Penny
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D066128:Gray Matter / Q000000981:diagnostic imaging / Q000254:growth & development*; D006803:Human Development / Q000502:physiology*; D006801:Humans; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008959:Models, Neurological; D015999:Multivariate Analysis; D017397:Prefrontal Cortex / Q000000981:diagnostic imaging / Q000254:growth & development*; D011627:Puberty / Q000502:physiology*; D055815:Young Adult
keywords: Ageing; Bayesian inference; Brain maturation; Connectivity; Dynamical systems; Longitudinal analysis; Structural brain mapping