The Neural Mechanisms of Split-belt Treadmill Adaptation in People With Multiple Sclerosis

Majority of people with multiple sclerosis experience difficulty with balance and mobility, leading to an increased risk of falls. The goal of this clinical trial is to learn about brain activity during walking adaptation in people with multiple sclerosis. Also, this clinical trial will test a form of nerve stimulation to see if it can improve walking performance. The main questions it aims to answer are: * What areas of the brain are the most active during walking adaptation? * Can nerve stimulation make walking adaptation more effective? Participants will walk on a treadmill where each leg will go a different speed which will create walking adaptation. At the same time, brain scans will occur. There will be two sessions of walking adaptation, one with nerve stimulation, and one without nerve stimulation. Researchers will compare people with multiple sclerosis to healthy young adults to see if there are differences in brain activity.