Objective: To investigate brain mechanisms and efficacy of an fMRI-neurofeedback protocol that targets the brain's motor circuits through the basal ganglia. Study design: Randomised controlled trial Study population: Patients with Parkinson's disease Investigation: In the experimental group, fMRI-neurofeedback will be administered in 4 separate sessions of about 2 hours each over approximately one month. The MRI measurement in each session will be approximately 60 minutes long and include upregulation training of brain activity in specific target areas by mental imagery. The fMRI signals are processed such that the patients get visual feedback about the success of the upregulation. In addition, patients are asked to practice the self-regulation strategies on a daily basis at home between the neurofeedback sessions. The control intervention will consist of mental imagery without neurofeedback. Main study parameters/endpoints: Post-interventional improvement of motor symptoms of PD as assessed by the Movement Disorder Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS) motor scale in the on-medication state. Nature and extent of the burden and risks associated with participation, benefit and group relatedness: This is a low-risk study where the main burden is participation time and MRI scans.