White matter matters for the control of human motor behavior.

In nearly all daily life activities, perfect control and coordination of our movements is required. During such (precise) movements, efficient collaboration (i.e., communication) within and among brain areas is of critical importance. This neural communication is accomplished via white matter pathways. Based on a large body of cross-sectional work, the notion has gained acceptance that individual variability in white matter structure is predictive of motor behavior. Moreover, evidence for white matter plasticity in response to motor skill learning is slowly emerging. However, it remains unclear which subcomponents of white matter particularly drive motor control. In view of the importance of white matter for normal brain functioning, and by extension human behavior, it is evident that injury-induced damage can have devastating consequences. Indeed, the disruption of white matter pathways in traumatic brain injury (TBI) is often associated with (persistent) motor dysfunction. However, given the conflicting findings in white matter metrics post-injury, it remains an open question what elements of white matter are particularly affected, and how these contribute to motor (dys)function. Therefore, I aim to significantly contribute to a deeper understanding of the particular importance of the dynamics of white matter microstructure in brain function and behavior.