This study looks at how the brain helps people with Parkinson's Disease (a condition that affects movement) walk better after training on a special treadmill called a split-belt treadmill (SBT). The study focuses on a part of the brain called the Posterior Parietal Cortex (PPC), which is believed to help transfer movement skills from the treadmill to regular walking.

Participants will visit the lab on three different days. On the first day, doctors will assess how well you walk and find the right spots on your body to use a machine called transcranial magnetic stimulation (TMS), which uses magnetic fields to activate parts of the brain. On the second and third days, you will receive either real TMS or pretend TMS (called sham) and do walking tests before and after the treadmill training.

• You will spend three separate days in the lab, with at least 48 hours between two of the visits.
• You will walk on a special treadmill for 30 minutes with breaks and do walking tests before and after.
• No prior experience with the split-belt treadmill is needed.