Browsing by Author "Kar, Preeti"

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    The brain's functional connectome in young children with prenatal alcohol exposure
    (Elsevier, 2019-01) Long, Xiangyu; Kar, Preeti; Gibbard, Ben; Tortorelli, Christina; Lebel, Catherine
    Prenatal alcohol exposure (PAE) can lead to altered brain function and structure, as well as lifelong cognitive, behavioral, and mental health difficulties. Previous research has shown reduced brain network efficiency in older children and adolescents with PAE, but no imaging studies have examined brain differences in young children with PAE, at an age when cognitive and behavioral problems often first become apparent. The present study aimed to investigate the brain's functional connectome in young children with PAE using passive viewing fMRI. We analyzed 34 datasets from 26 children with PAE aged 2-7 years and 215 datasets from 87 unexposed typically-developing children in the same age range. The whole brain functional connectome was constructed using functional connectivity analysis across 90 regions for each dataset. We examined intra- and inter-participant stability of the functional connectome, graph theoretical measurements, and their correlations with age. Children with PAE had similar inter- and intra-participant stability to controls. However, children with PAE, but not controls, showed increasing intra-participant stability with age, suggesting a lack of variability of intrinsic brain activity over time. Inter-participant stability increased with age in controls but not in children with PAE, indicating more variability of brain function across the PAE population. Global graph metrics were similar between children with PAE and controls, in line with previous studies in older children. This study characterizes the functional connectome in young children with PAE for the first time, suggesting that the increased brain variability seen in older children develops early in childhood, when participants with PAE fail to show the expected age-related increases in inter-individual stability.
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    Early Influences on Brain Development in Preschool Children
    (2021-09) Kar, Preeti; Lebel, Catherine; Pike, Bruce; McMorris, Carly
    During early childhood, extensive brain development takes place which underlies foundational cognitive and behavioural learning. Early environmental factors during the prenatal period and first few postnatal years can play important roles in promoting or hindering this period of brain development. Breastfeeding in infancy and alcohol use in pregnancy are both maternal behaviors with long-term impacts on children, but their downstream effects on the brain are not well-understood during early childhood. My thesis used diffusion tensor imaging to assess white matter development in young children (2-7 years) in association with 1) breastfeeding exclusivity status at 6 months of age and the total duration of any breastfeeding, as well as 2) prenatal alcohol exposure (PAE). First, I found that breastfeeding exclusivity and duration were associated with global and regional white matter microstructure, even after controlling for perinatal and sociodemographic factors, and these findings differed by sex. Second, I found that young children with PAE showed altered white matter microstructure cross-sectionally and longitudinally compared to unexposed controls. Third, measures of white matter in motor tracts were associated with motor performance in unexposed typically developing children, but these structure-function associations were not present in young children with PAE. This work highlights the dynamic and complex brain development taking place in early childhood and indicates how environmental variables during the prenatal and postnatal period, such as breastfeeding and PAE, moderate brain circuitry and behaviors in young children. This research has broad implications for clinical, policy, and health education strategies to promote breastfeeding and prevent PAE and ultimately support mothers and children.