This study explores brain activity in people with movement disorders like Parkinson's disease (PD) and essential tremor (ET). These disorders affect how you move, but can also cause problems like depression, memory loss, and trouble speaking. The researchers want to learn how the brain's activity changes in these conditions. They use a technique called deep brain stimulation (DBS) during surgery to study brain signals. DBS is already used to help with movement issues in PD but might not help or could even make some non-movement symptoms worse. This study aims to find out more about these effects and improve treatments.

• The study involves brain recordings during DBS surgery.
• Participants must be at least 18 years old and willing to take part in study activities.
• Not suitable for those unable to consent, surgical risks, or pregnancy.