Andrew Alexander, PhD

Andrew Alexander, PhD Slide of the Week

Mapping White Matter Microstructure in the One Month Human Brain

Legend: Matched coronal and axial slices through the of the population averaged diffusion tensor imaging (DTI) and neurite orientation dispersion and density imaging (NODDI) parameters (Left). Gestation corrected age relationships of fractional anisotropy (FA), radial diffusivity (RD) and neurite density (νIC) for left hemisphere white matter regions. (Right) The legend under each column indicates the depicted white matter regions.

Citation: Dean, D.C., Planalp, E.M., Wooten, W., Adluru, N., Kecskemeti, S.R., Frye, C., Schmidt, C.K., Schmidt, N.L., Styner, M.A., Goldsmith, H.H., Davidson, R.J., Alexander, A.L., 2017. Mapping White Matter Microstructure in the One Month Human Brain. Sci Rep 7, 9759.

Abstract: White matter microstructure, essential for efficient and coordinated transmission of neural communications, undergoes pronounced development during the first years of life, while deviations to this neurodevelopmental trajectory likely result in alterations of brain connectivity relevant to behavior. Hence, systematic evaluation of white matter microstructure in the normative brain is critical for a neuroscientific approach to both typical and atypical early behavioral development. However, few studies have examined the infant brain in detail, particularly in infants under 3 months of age. Here, we utilize quantitative techniques of diffusion tensor imaging and neurite orientation dispersion and density imaging to investigate neonatal white matter microstructure in 104 infants. An optimized multiple b-value diffusion protocol was developed to allow for successful acquisition during non-sedated sleep. Associations between white matter microstructure measures and gestation corrected age, regional asymmetries, infant sex, as well as newborn growth measures were assessed. Results highlight changes of white matter microstructure during the earliest periods of development and demonstrate differential timing of developing regions and regional asymmetries. Our results contribute to a growing body of research investigating the neurobiological changes associated with neurodevelopment and suggest that characteristics of white matter microstructure are already underway in the weeks immediately following birth.

About the Lab: Alexander’s research focuses on the use of magnetic resonance imaging (MRI) for mapping and measuring the functional and structural organization of the human brain. These techniques are used to investigate the brain in both typically developing individuals and subjects with developmental disorders including autism. Functional MRI (fMRI) is used to assess brain regions associated with cognition and affect and their dysfunctions in these populations. Diffusion tensor MRI (DT-MRI) is used to study the patterns of structural connectivity between brain activity regions. Anatomic imaging methods are used to assess longitudinal structural changes in brain regions. These measurements are ultimately compared with measures of affect, behavior and cognition in specific population groups.

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