While there is much evidence of grey matter changes in the adult brain, this study shows changes to white matter in the adult brain due to specific training: juggling!
Paper — Scholz, et al. 2009. Training Induces Changes in White Matter Architecture.
Although experience-dependent structural changes have been demonstrated in adult gray matter, there is little evidence for such changes in white matter. Using diffusion imaging, we detected a localized increase in fractional anisotropy, a measure of microstructure, in white matter underlying the intraparietal sulcus, following training of a complex visuo-motor skill. This provides the first evidence for training related changes in white matter structure in the healthy human adult brain.
The “visuo-motor skill” the subjects learned was juggling. In other words, a hard-to-master skill, not unlike many in sports.
Why they may have seen the results they did:
FA in part reflects white matter properties such as axon caliber and myelination. Changes in these properties might underlie behavioral improvements by altering conduction velocity and synchronisation of nervous signals. Previous reports suggest that electrical activity within an axon could regulate its myelination over a time course of days to weeks. Activity-dependent myelo-modulation, which would be expected to influence FA, is therefore a potential mechanism through which the functional properties of white matter are affected by experience. Changes in other structural features of the white matter, such as axon diameter (which could itself be regulated by myelin), or packing density, could also underlie the results found here.
… we provide the first evidence for experience dependent changes in white matter microstructure in healthy human adults.
Now go lift something heavy,