This is a feasibility and exploratory study consisting of two parts: first, a cross-sectional (one-time) biomarker measurement comparing BDNF-TrkB (Brain-derived neurotrophic factor (BDNF) and its receptor, TrkB,) signaling and cortical plasticity in patients diagnosed with Parkinson's Disease (PD) vs. healthy controls matched by age. Second, a prospective, randomized, double blind trial of Transcranial Magnetic Stimulation (TMS) MAGSTIM Rapid2 Therapy System (TMS) (real or Sham) and aerobic exercise. This exploratory feasibility study will look at BDNF-TrkB signaling and cortical plasticity.