Researchers are studying movement problems in people with Parkinson's disease (PD), especially those who experience "Freezing of Gait" (FOG). This occurs when a person feels stuck and can't move their feet properly. To understand this, scientists will look at two things: how the brain's balance system (vestibular) and thinking parts (cortical) work during movement changes. They will use techniques like electrical vestibular stimulation (EVS) and electroencephalography (EEG) to measure activity in these areas. The goal is to find new ways to help people with PD move better and reduce falls.

• **Study Participation**: For individuals with PD, ages 40-80, & healthy adults 21-80.
• **Study Procedures**: Includes noninvasive tests; no assistive devices needed for walking.
• **Exclusions**: Certain medical conditions, surgeries, or devices may disqualify participation.