Evidence of Lateralized White Matter Plasticity: A Longitudinal Study of Balance Performance in Nonexpert Healthy Adults.

Training-induced plasticity by practicing expert skills has been of particular interest; however, little is known about white matter plasticity for improving a fundamental element of body function, such as balance or postural control. This study explored white matter plasticity in nonexpert healthy adults, based on stepwise balance training. Seventeen participants were included and performed a home-based balance training program for 4 weeks (30 minutes/day, 3 days/week). Before commencing training, they underwent a baseline diffusion tensor imaging scan. A second scan was acquired at the end of the 4-week training. Lateralized balance load was applied on the right leg to contrast any lateralized effect on the white matter tracts. The balance function was assessed using the Community Mobility & Balance Scale. We examined changes in the fractional anisotropy values of the tracts of interest between pre- and post-training. After the 4-week training, the fractional anisotropy values were enhanced in the right superior cerebellar peduncle, transverse pontine fiber, body of the corpus callosum, left fornix, and left uncinate fasciculus. The Community Mobility & Balance Scale score improved after 4-week training, but an association with changes in fractional anisotropy values cannot be evaluated due to the ceiling effect of the balance assessment tools. Balance training can strengthen the cerebro-cerebellar and interhemispheric structural connections and induce microstructural changes in the limbic structures, including the fornix and uncinate fasciculus. The effect of a lateralized balance load could be projected to the specific white matter tracts in a lateralized manner.