Outcome measures will be obtained before, after the 2-week intervention and 4 weeks post-intervention, and will include 1) clinical measures (FAC, gait analysis, 10 meter walk test, 6 minute walk test, timed up and go), 2) cortical excitability measures using TMS (changes in resting motor threshold (RMT), or active motor threshold (AMT) of the affected and unaffected TA and short-interval cortical inhibition/facilitation (SICI/SICF), measured according to the technique of Rossini et al. (1994)), 3) MRI measures including diffusion tensor tractography (DTT), resting state protocols and GABA scan. 4) Genotyping and blood level of BDNF. 5) Psychological and cognitive assessment including Beck Depression Inventory (BDI), Fatigue Severity Scale, forward and backward digit span.