This study is exploring how a type of brain stimulation called temporal interference stimulation (TIS) affects people with Parkinson's disease (PD). TIS targets specific parts of the brain: the subthalamic nucleus (STN) or globus pallidus internus (GPi). The study includes 18 adults with PD, split into two groups. They will receive a 20-minute TIS session every day for a week. Doctors will check their movement symptoms before and after each session. The study also uses advanced brain scans (fMRI) and brain activity measurements (EEG) to see changes in brain function.

**Key Points**:

• Participants will attend daily sessions for 7 days.
• Doctors will monitor safety and side effects, like skin reactions.
• Participants must be able to walk for at least 5 minutes on their own.

Participants need to be at least 40 years old, diagnosed with PD, and taking medication that helps their symptoms. They should not have other serious health issues or be in other studies. This research aims to find out more about how TIS can help people with PD.