Primary Outcome Measures:
- The ERD and ERS patterns of coordination between the STN and cortical regions in the termination of volitional movement in PD patients. [ Time Frame: after deep brain stimulation 4th day ] [ Designated as safety issue: Yes ]
- To investigate the functional connectivity between the sub-thalamic nucleus and cerebral cortex on movement initiation and termination in PD patients.
- To examine phase leading roles of sub-thalamic nucleus and cerebral cortex in conducting volitional movements and will mainly focus on the movement termination.
The project will investigate the roles of cortical regions, sub-thalamic nucleus and pedunculo-pontine nucleus in the preparation of volitional movement termination in patients with Parkinson's disease (PD)receiving deep brain stimulation. Currently there are two models of inhibitory preparation of volitional movements. The "withdrawal mechanism" posits the explanation that movement termination is due to the"shutting off" of the activated neuralcircuitry, whereas the "inhibition mechanism" suggests that inhibitory neural structures are activated to terminate the voluntary movement. These hypotheses were deduced from the study of scalp movement-related cortical potential recordings and how the deep structures involved in the execution in movement termination is uncertain. Movement preparation prior to movement onset (Mon) has been addressed in both scalp recordings of MRCP and from recent studies of STN in PD patients. However,the electro-physiologic information concerning the role of STN in the preparation of movement offset (Moff)is less understood. In our pilot study, we have found that high-beta event-related de-synchronization (ERD)appeared earlier (3 seconds prior to Mon) than those of low-beta and alpha for the Mon phasic movement.There was no alpha ERD for the Mon tonic movement. Alpha, low-beta, and high-beta ERD all appeared about 1 second prior to the Moff tonic movement. These findings suggest that STN participates in the preparation of volitional movement termination but via different mechanism from that in movement initiation.Unlike asynchronous ERD frequency bands present in movement initiation, a simultaneous ERD across wide frequency bands in STN may play a pivotal role in terminating volitional movement. Since there is tight connection between the cortical regions and STN, it is intriguing to know the relationship of these oscillatory patterns between the deep and superficial neural structures. In the current proposal, we will examine the patterns of ERD and ERS prior to Mon and Moff of tonic movements in both cortical and STN regions and determine the temporal relationship among them.