Browsing by Author "Kramer, Larry A."
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Item Development and aging of the healthy human brain uncinate fasciculus across the lifespan using diffusion tensor tractography(Brain Research, 2009-06) Hasan, Khader M.; Iftikhar, Amal; Kamali, Arash; Kramer, Larry A.; Ashtari, Manzar; Cirino, Paul T.; Papanicolaou, Andrew C.; Fletcher, Jack M.; Ewing-Cobbs, LindaThe human brain uncinate fasciculus (UF) is an important cortico-cortical white matter pathway that directly connects the frontal and temporal lobes, although there is a lack of conclusive support for its exact functional role. Using diffusion tensor tractography, we extracted the UF, calculated its volume and normalized it with respect to each subject's intracranial volume (ICV) and analyzed its corresponding DTI metrics bilaterally on a cohort of 108 right-handed children and adults aged 7-68 years. Results showed inverted U-shaped curves for fractional anisotropy (FA) with advancing age and U-shaped curves for radial and axial diffusivities reflecting white matter progressive and regressive myelination and coherence dynamics that continue into young adulthood. The mean FA values of the UF were significantly larger on the left side in children (p = 0.05), adults (p = 0.0012) and the entire sample (p = 0.0002). The FA leftward asymmetry (Left > Right) is shown to be due to increased leftward asymmetry in the axial diffusivity (p < 0.0001) and a lack of asymmetry (p > 0.23) for the radial diffusivity. This is the first study to provide baseline normative macro and microstructural age trajectories of the human UF across the lifespan. Results of this study may lend themselves to better understanding of UF role in future behavioral and clinical studies.Item Neuropsychological profiles of children with aqueductal stenosis and spina bifida myelomeningocele(Journal of the International Neuropsychological Society, 2013-02) Hampton, Lyla E.; Fletcher, Jack M.; Cirino, Paul T.; Blaser, Susan; Kramer, Larry A.; Dennis, MaureenWe compared neuropsychological profiles in children with shunted hydrocephalus secondary to aqueductal stenosis (AS), a rare form of congenital hydrocephalus, and spina bifida myelomeningocele (SBM), a common form of congenital hydrocephalus. Participants were 180 children with shunted hydrocephalus grouped according to etiology: SBM (n = 151), AS (n = 29), and typically developing (TD; n = 60) individuals. The group with AS performed below the TD group on all tasks except for reading, and their overall performance was higher than the group with SBM, who had the lowest performance in the sample. Both clinical groups significantly differed from the TD group on tasks of spatial function, concept formation, motor function, and memory. Performance of the subgroup of AS children with normal cerebellum status approximated that of the TD group, while those with cerebellar anomalies performed lower than others with AS. Cerebellar abnormalities (present in the whole SBM group and in a subset of the AD group) are associated with more compromise of cognitive as well as motor function.