Understanding the relationship between structure and function in the human brain is a key interest in neuroscience. In recent years the focus is turning to understanding the role of the white matter in human cognition, brain function and neurological disorders. I am developing tools to study the 3D morphology and shape variability of major human neuronal tracts using a synergy of tools from neuroscience, computational geometry, computer vision and machine learning. I am modeling such variability within and between individuals and populations, with regards to normal and pathological aging and development. This work will open new opportunities to quantitatively analyze properties of the human brain that are to date unexplored and ultimately lead to better understanding of the role of white matter in human cognition.