**Neural Control of Breathing in Parkinson's Disease** Parkinson's Disease (PD) is a brain disorder that gets worse over time, causing problems like difficulty breathing. This study looks at how the brain controls breathing in people with PD compared to healthy people. The researchers will use special tests to see if the brain's control of breathing is different in those with PD. These tests include the Hypercapnic Ventilatory Response (HCVR), which checks how breathing changes when carbon dioxide (CO2) levels rise, and Transcranial Magnetic Stimulation (TMS), which uses magnets to study brain activity related to breathing. - **Study Duration & Visits**: Participants will complete the study in one visit, but it may feel long and tiring. Breaks are included. - **Compensation**: There is no direct benefit or compensation for participants. - **Risks**: The study is safe with no invasive procedures, but participants should be aware of the time commitment. Participants must be healthy adults over 18 or adults with PD confirmed by a specialist. It's important to understand the study's purpose and be willing to follow study requirements. Exclusions include other brain or lung diseases, pacemakers, and pregnancy.