Development and aging of the healthy human brain uncinate fasciculus across the lifespan using diffusion tensor tractography


The 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.



Diffusion tensor imaging, Fiber tracking, Uncinate fasciculus, Child, Adults, Brain development, Aging, Lifespan


Copyright 2009 Brain Research. This is a post-print version of a published paper that is available at: Recommended citation: Hasan, Khader M., Amal Iftikhar, Arash Kamali, Larry A. Kramer, Manzar Ashtari, Paul T. Cirino, Andrew C. Papanicolaou, Jack M. Fletcher, and Linda Ewing-Cobbs. "Development and Aging of the Healthy Human Brain Uncinate Fasciculus Across the Lifespan Using Diffusion Tensor Tractography." Brain Research 1276, no. 18 (2009): 67-76. doi: 10.1016/j.brainres.2009.04.025. This item has been deposited in accordance with publisher copyright and licensing terms and with the author's permission.