The purpose of this research study is to investigate the effectiveness of MS Disease modifying medications on cognitive fatigue in persons with relapsing remitting multiple sclerosis (RRMS). Cognitive fatigue is the kind of fatigue that occurs after intense mental concentration as after a session of problem solving.

The researchers aim is to investigate the effects of disease modifying treatments on cognitive fatigue and on specific brain areas that have been shown to underlie cognitive fatigue in individuals with Multiple Sclerosis (MS). The researchers will investigate the effects on the cognitive fatigue that develops during the performance of a demanding task, and also on how cognitive fatigue changes as a function of duration of treatment.

Inclusion Criteria:

• Age between 18-64.
• Relapsing remitting multiple sclerosis
• Been newly prescribed a new disease modifying medication for MS (either Ocrevus or Copaxone)
• or healthy volunteer who can speak English fluently.

Exclusion Criteria:

• History of head injury, stroke, seizures, or any other significant neurological event other than MS
• Flare up of MS symptoms within the past month.
• History of significant psychiatric illness (for example, bipolar disorder, schizophrenia, or psychosis) or a current diagnosis of Major Depressive Disorder.
• Pacemaker or other implanted electrical device, brain stimulator, aneurysm clip (metal clips on the wall of a large artery), metallic prostheses (including metal pins and rods, heart valves, and internal hearing aids [cochlear implants]), permanent eyeliner, implanted delivery pumps, or shrapnel fragments.
• left handed.
• Not able to have an MRI

Individuals who have Relapsing remitting Multiple Sclerosis and Healthy Volunteers