Objective: To assess the dynamic brain responses during planning motor fMRI task in an early-stage cohort of Parkinson’s disease patients.

Background: Parkinson’s disease (PD) is characterized by the presence of motor symptoms such as bradykinesia, rigidity and tremor. The dysfunction of dopaminergic striato-cortical pathways results in the progressive impairment in planning and executing actions. In this study, we aimed to investigate the dynamic functional activity of the striato-cortical circuitry by using motor planning fMRI tasks in early-stage PD subjects.

Methods: 33 early-stage right-handed PD subjects and 18 age and gender matched healthy controls underwent a motor task fMRI study in the practically defined off-medication state. The present functional task was subdivided in three sub-tasks pertaining simple motor execution, motor planning to movement and no movement. Behavioural performance and task-related activation analysis of the functional blocks was performed in order to investigate the difference between study groups. Additional regression analysis of task-related activation with behavioural measures and motor examination was performed in the PD cohort.

Results: Behavioural analysis showed increased mean response latencies in the PD cohort than healthy group, which in turn correlated with total UDPRS III (p<0.05). When assessed motor planning to movement vs no movement, the PD group compared to controls showed functional activations in bilateral premotor and left primary motor cortex. In addition when evaluating motor planning to movement vs simple motor execution, the PD group compared to controls displayed activations in bilateral premotor cortex, left primary motor and sensorimotor cortex. Moreover, compensatory striatal and primary motor activations positively correlated with UPDRS III and mean response latencies.

Conclusions: Our results provide evidence that at early stages of Parkinson’s disease subjects display significant compensatory functional activations in striatum, motor and parietal cortex related to motor planning task which in PD which are closely associated with motor severity.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/compensatory-functional-activations-in-early-stage-parkinsons-disease-a-cross-sectional-motor-planning-fmri-study/