This study looks at using a person's own nerve tissue (called autologous peripheral nerve tissue) to help with Parkinson's Disease (PD) symptoms during brain surgery called deep brain stimulation (DBS). DBS is a procedure that helps control movement problems by placing tiny wires in the brain. In this study, the nerve tissue is placed in parts of the brain called the nucleus basalis of Meynert (NBM) or substantia nigra (SN) to see if it can help improve thinking and movement. The study will include 24 people with PD, aged 45-75, who are already having DBS surgery. Participants will be checked on their thinking, movement, daily activities, and quality of life before surgery, and then several times after, up to two years.

• The study lasts for three years with follow-up visits up to 24 months post-surgery.
• It involves assessments before and after surgery to monitor changes.
• Participants need to have access to a specific nerve in their leg for the procedure.