Biology subjects

Malpas, C.

Publications and source records attributed to Malpas, C..

2 recordsLinked to original sources

bioRxiv2017

Age, sex, and puberty related development of the corpus callosum: a multi-technique diffusion MRI study

PurposeThe corpus callosum is integral to the central nervous system, and continually develops with age by virtue of increasing axon diameter and ongoing myelination. Magnetic resonance imaging (MRI) techniques offer a means to disentangle these two aspects of white matter development. We investigate the profile of microstructural metrics across the corpus callosum, and assess the impact of age, sex and pubertal development on these processes.\n\nMethodsThis study made use of two independent paediatric populations. Multi-shell diffusion MRI data were analysed to produce a suite of diffusion tensor imaging (DTI), neurite orientation density and dispersion imaging (NODDI), and apparent fibre density (AFD) metrics. A multivariate profile analysis was performed for each diffusion metric across 10 subdivisions of the corpus callosum.\n\nResultsAll diffusion metrics significantly varied across the length of the corpus callosum. AFD exhibited a strong relationship with age across the corpus callosum (partial{eta} 2 = .65), particularly in the posterior body of the corpus callosum (partial{eta} 2 = .72). In addition, females had significantly higher AFD compared with males, most markedly in the anterior splenium (partial{eta} 2 = .14) and posterior genu (partial{eta} 2 = .13). Age-matched pubertal group differences were localised to the splenium.\n\nConclusionWe present evidence of a strong relationship between apparent fibre density and age, sex, and puberty during development. These results are consistent with ex vivo studies of fibre morphology, providing insights into the dynamics of axonal development in childhood and adolescence using diffusion MRI.\n\nTarget journalsBrain Structure & Function; HBM; NeuroImage; Developmental Cognitive Neuroscience

neuroscience↗

bioRxiv2017

Different Brain Networks Underlying Intelligence In Autism Spectrum Disorders And Typically Developing Children

BackgroundThere has been sustained clinical and cognitive neuroscience research interest in how network correlates of brain-behaviour relationships might be altered in Autism Spectrum Disorders (ASD) and other neurodevelopmental disorders. As previous work has mostly focused on adults, the nature of whole-brain connectivity networks underlying intelligence in pediatric cohorts with abnormal neurodevelopment requires further investigation.\n\nMethodsWe used network-based statistics (NBS) to examine the association between resting-state functional Magnetic Resonance Imaging (fMRI) connectivity and fluid intelligence ability in male children (n=50) with Autism Spectrum Disorders (ASD; M=10.45, SD=1.58 years and in controls (M=10.38, SD=0.96 years) matched on fluid intelligence performance, age and sex. Repeat analyses were performed in independent sites for validation and replication.\n\nResultsDespite being equivalent on fluid intelligence ability to strictly matched neurotypical controls, boys with ASD displayed a subnetwork of significantly increased associations between functional connectivity and fluid intelligence. Between-group differences remained significant at higher edge thresholding, and results were validated in independent-site replication analyses in an equivalent age and sex-matched cohort with ASD. Regions consistently implicated in atypical connectivity correlates of fluid intelligence in ASD were the angular gyrus, posterior middle temporal gyrus, occipital and temporo-occipital regions.\n\nConclusionDevelopment of fluid intelligence neural correlates in young ASD males is aberrant, with an increased strength in intrinsic connectivity association during childhood. Alterations in whole-brain network correlates of fluid intelligence in ASD may be a compensatory mechanism that allows equal task performance to neurotypical peers.

neuroscience↗