Dynamics of the extended subthalamic-pallidal complex in deep brain stimulation for Parkinson´s disease

We extend the simple firing-rate model of the complex, composed of the subthalamic nucleus (STN) and the external segment of the globus pallidus (GPe), by introducing the internal segment of the globus pallidus (GPi) to investigate the dynamics of the basal ganglia system (BGS). Through numerical simulation we show that, the system can reproduce both the physiological and pathological state of the subthalamo-pallidal complex. Furthermore, the dynamics of the extended complex in deep brain stimulation (DBS) for Parkinson´s disease (PD) is also studied. It is shown that high frequency stimulation of STN can regularize the GPi firing, and functionally restore TC responsiveness. We also find that low frequency DBS can also alleviate the motor symptoms caused by a weakening of intra-GPe connections. The presented results could have important implications for understanding the underlying mechanisms of DBS.