This study is testing a new way to help people with Parkinson's disease move better. It uses a technique called Transcranial Temporal Interference Stimulation (TIS). TIS is a type of brain stimulation that targets a brain area called the internal globus pallidus (GPi). The study wants to see if TIS can improve movement and if these improvements last up to two months. Participants will be split into two groups: one will receive real TIS, and the other will receive a fake version (sham stimulation) to compare results.

• Participants will have 10 sessions of TIS over two weeks.
• Movement and brain activity will be assessed before, during, and after the treatment.
• Follow-up assessments will happen at 2, 4, and 8 weeks after treatment.

To join, you must be diagnosed with Parkinson's after age 40, have stable medicine, and meet other health criteria. You can’t join if you have certain medical conditions or treatments. This study involves multiple visits and assessments, which may require some time commitment.