This study focuses on understanding brain activity related to non-motor symptoms in people with Parkinson's disease (PD) and essential tremor (ET). These symptoms can include depression, trouble thinking, and slower actions. During deep brain stimulation (DBS) surgery, doctors will record brain activity to learn more about these issues. DBS is a surgery where electrodes are placed in the brain to help with movement problems. However, it doesn't always help with thinking problems.
**Key Points to Consider:**
- This study involves surgery, which includes brain recordings.
- You must have Parkinson's disease or essential tremor and be eligible for surgery.
- You cannot join if under 18 or have certain medical histories.