Effects of Repetitive Transcranial Magnetic Stimulation (rTMS)-Primed Self-controlled Practice on Motor Behavior, Psychosocial Functioning, and Neurophysiological Mechanisms in People With Parkinson's Disease

Parkinson's disease (PD) is commonly associated with impaired motor learning and reduced motivation, both of which can negatively influence rehabilitation outcomes. Prior cross-sectional evidence suggests that providing individuals with PD self-controlled access to training parameters enhances motor learning, increases motivation, and facilitates cognitive processing. However, the effects of self-controlled practice implemented across repeated training sessions remain underexplored. Moreover, given that dysfunction of fronto-striatal circuits in PD may limit the neuroplastic response to motor training alone, adjunctive neuromodulatory priming approaches such as repetitive transcranial magnetic stimulation (rTMS) may be required to optimize therapeutic efficacy. To date, it remains unclear whether rTMS priming combined with self-controlled motor training yields superior clinical benefits, and whether stimulation of different cortical targets produces differential effects. In particular, the dorsolateral prefrontal cortex (DLPFC), a key region involved in cognitive control and motivation, may offer distinct therapeutic effects compared with stimulation of the primary motor cortex (M1). This study aims to investigate the effects of rTMS priming over the DLPFC or M1, followed by self-controlled motor training, in individuals with PD, and to compare these effects with a sham stimulation condition.

This single-blinded, randomized control trial will recruit 90 individuals with PD, who will be matched into 45 pairs and randomly assigned to one of three stimulation conditions: DLPFC, M1, or sham. Within each pair, one participant will be allocated to a self-controlled practice condition, and the other to a yoked (paired-control) condition that receives identical training content determined by their matched counterpart. Each participant will undergo 12 intervention sessions. In each session, rTMS will be applied first as a priming intervention, followed immediately by 45 minutes of standardized physical therapy-based motor training. For the DLPFC group, stimulation will target the left DLPFC; for the M1 group, stimulation will be applied over the M1 contralateral to the more affected limb; and for the sham condition, the coil will be rotated 90 degrees to mimic stimulation without effective cortical activation. During the training phase, participants in the self-controlled condition will be allowed to select aspects of their practice content, whereas yoked participants will follow the corresponding selections made by their matched partner.

The primary outcome measure is the Unified Parkinson's Disease Rating Scale (UPDRS). Secondary outcomes include assessments of cognitive function, apathy, non-motor symptoms, gait performance, balance, functional mobility, falls efficacy, and quality of life. Neurophysiological outcomes will be assessed using single- and paired-pulse TMS to evaluate corticospinal excitability and cortico-cortical connectivity, particularly between DLPFC and M1 networks. All assessments will be conducted in the medication-on state by blinded evaluators at baseline, immediately post-intervention, and at one-month follow-up. Data will be analyzed using mixed-effects repeated-measures ANOVA to examine group-by-time interactions and intervention effects. This study seeks to determine whether rTMS priming over cognitive-control versus motor networks differentially enhances the efficacy of self-controlled motor training, and whether such combined interventions can induce sustained improvements in motor and non-motor outcomes in PD.