Reorganization of motor system in Parkinson's disease

We investigated adaptive reorganization in Parkinson's disease (PD) by fMRI using a passive movement task and compared the brain activation patterns of 10 patients with left- versus right-sided dominant symptoms. Five healthy controls were also investigated with the same settings.

We grouped patients according to the predominant side of symptoms; thus, a right-sided dominant and a left-sided dominant group was formed. The paradigm consisted of a 4-finger passive movement task, which altered with resting states. For each subject, this examination was performed twice: on the left and on the right hand separately.

In healthy controls, motor-related areas contralateral to the moving fingers showed activation on fMRI. Concerning PD patients, motor-related areas of the ipsilateral hemisphere - including the primary motor cortex, supplementary motor area, and basal ganglia - seemed to be involved in the motor reorganization in PD. However, we could only demonstrate this reorganization in patients with right-sided dominant symptoms.

We suggest that the human brain in PD tries to compensate for the failure of the basal ganglia motor loop by employing alternative (ipsilateral) motor pathways, indicating that a complex reorganization can also take place in disorders like PD which affect the whole motor-related network.