Investigating the Effects of Transcranial Direct Current Stimulation to Different Brain Regions on Ankle Tracking Motor Learning, Motor Adaptation, and Brain Connectivity in Healthy Middle-aged and Older Adults and Patients With Subcortical Stroke

During the 5-day skill acquisition phase, all participants will undertake a 20-minute session of learning a sequential ankle tracking task with their non-dominant (for healthy adults) or affected (for patients with stroke) foot each day, using a custom-built ankle tracking system. The cM1 group will receive AtDCS stimulation at 2 mA during acquisition phase.

During the 5-day skill acquisition phase, all participants will undertake a 20-minute session of learning a sequential ankle tracking task with their non-dominant (for healthy adults) or affected (for patients with stroke) foot each day, using a custom-built ankle tracking system. The cPPC group will receive AtDCS stimulation at 2 mA during acquisition phase.

During the 5-day skill acquisition phase, all participants will undertake a 20-minute session of learning a sequential ankle tracking task with their non-dominant (for healthy adults) or affected (for patients with stroke) foot each day, using a custom-built ankle tracking system. The iCBM group will receive AtDCS stimulation at 2 mA during acquisition phase.

For the Sham group, the montages of the paired electrode placements will be randomly selected from the other three pairs using blocks of size 3, so that the three types of montages will have equal opportunities to be used in the Sham group. The intensity will be set at 0 mA for the Sham group. There will be a 30-second ramp-up for the Sham group. Once the current reaches 2 mA in the ramp-up period, it will drop to 0 mA for the entire 20 minutes during learning for the Sham group.