Mapping White Matter Microstructure in the One Month Human Brain

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.

Figure 1

Overall schematic depicting the acquisition, processing, and analyses of the current study.

Figure 2

Coronal raw DTI (FA, MD, AD, and RD) and NODDI (ν_IC, ODI, and ν_ISO) estimates from four representative infants. The sex of the infant is denoted in the bottom panel. The optimized diffusion protocol resulted in high quality DWI data and parameter maps.

Figure 3

Matched coronal and axial slices through the of the population averaged DTI and NODDI parameters.

Figure 4

Representative scatter plots of the gestation corrected age relationships observed for the posterior thalamic radiations. Points correspond to the mean values from the posterior thalamic radiations. In general, increases of FA, ν_IC, and ODI and decreases of diffusivity measures were observed across the majority of white matter regions.

Figure 5

Combined gestation corrected age relationships of FA, RD and ν_IC for white matter regions of the left hemisphere. The legend under each column indicates the depicted white matter regions.