To investigate feasibility of basal-ganglia regions as fMRI-neurofeedback targets in Parkinson's patients and evaluate self-regulation success

This is a single-group proof of mechanism study of Parkinson's Disease (PD) patients receiving neurofeedback (NF) training using supplementary motor area (SMA) and basal ganglia as target areas. At the start of the screening session, consent will be taken. Subsequently, the screening assessment will be performed to determine inclusion and exclusion criteria. After inclusion in the study has been established, the NF sessions at the MRI scanner will be scheduled. The participants will be invited for up to three NF sessions. This will total up to a maximum of four visits, one for screening and up to three for the NF sessions. Due to the feasibility nature of the study, the optimal number of sessions for the patient cohort to learn the NF regulation is unknown. Therefore, flexibility has been introduced in the design to facilitate learning in case it is necessary. The NF training is modelled on the investigators' previous work.

Each NF session will consist of one anatomical scan, one localizer run, and four functional NF runs. The localizer run will be used to identify individualized brain activation patterns in the participants. Each NF run is a measurement sequence that will consist of ten blocks: five regulation blocks and five rest blocks. The participants will be asked to upregulate (increase) their brain activity, which will be displayed on a thermometer bar, during the regulation blocks. During the rest blocks, the participants will be asked to relax. The study will employ a crossover design with two conditions. In one condition the participants will receive feedback on the thermometer bar from the SMA region and in the second condition the participants will receive feedback from the basal ganglia region. Two of the NF runs will be with the SMA condition and two will be with the basal ganglia condition. Both runs in each condition will take place consecutively, i.e., either the first two runs will be SMA and the second two runs will be basal ganglia or vice versa. The sessions will be counter balanced.

At the last NF session, a post-training assessment will be conducted during which the participants will be debriefed about the study. NF is an individualized training method, and therefore, individual differences in learning success are expected during the study, which can lead to different expectations from the subjects. However, since this is an investigation of the feasibility of the approach, all forms of performance are useful datapoints and participants will be debriefed about their valuable contribution to make sure that no outcome is conceived as negative.

Inclusion Criteria:

• Diagnosis of Parkinson's disease (see 4.1) according to Movement Disorder Society (MDS) clinical diagnostic criteria (Postuma et al., 2015).
• Disease stage 1-3 according to the Hoehn and Yahr Scale

Exclusion Criteria:

• Exclusion criteria for MRI (e.g., cardiac pacemaker, certain metallic implants)
• History of psychotic disorder, bipolar disorder, or psychotic depression
• Current use of illegal drugs (any in the last four weeks)
• Current excessive alcohol consumption that interferes with daily functioning
• Advanced cognitive impairment (MoCA <24) or dementia

Patients with Parkinson's disease as per inclusion/ exclusion criteria