It is known that high frequency subthalamic nucleus deep brain stimulation (STN DBS) is very effective for improving the appendicular motor symptoms of Parkinson?s disease (PD) but stimulation often worsens inhibitory control. Our laboratory?s previous work has revealed that bilateral high frequency stimulation (? 130 Hz) resulted in an increase in inhibitory error rate on the antisaccade task, a cognitively demanding eye movement task. My previous work has found that the adjustment of stimulation parameters can modify performance on the antisaccade task. Increasing stimulation amplitude was found to increase inhibitory error rate. Stimulation at lower frequencies has shown an improvement in axial symptoms of PD and even performance on a cognitive control task compared to high frequency stimulation. However, it is unknown if stimulation frequency modifies inhibitory control performance on the antisaccade task. The neurophysiological mechanisms of how STN DBS results in inhibitory control dysfunction and worsens performance on the antisaccade task are also unknown. This study involves participants with PD and STN DBS completing the antisaccade task while we collect EEG and eye movement data. Participants will be tested on 4 different stimulation frequency conditions. To our knowledge, this data will be the first of its kind to evaluate the cortical mechanisms associated with inhibitory control at different STN DBS frequencies.
The specific aims of this research proposal will address gaps in the existing knowledge about the mechanisms of inhibitory control impairment with STN DBS. In addition, the proposed work will provide new insight into the effect of stimulation frequency on inhibitory control and cortical oscillatory activity.
Aim 1 will investigate the effect of STN DBS and stimulation frequency on inhibitory control performance, measured by inhibitory error rate, on the antisaccade task.
Aim 2 will examine the effect of STN DBS and stimulation frequency on event-related cortical oscillations during the antisaccade task.
Aim 3 will address the relationship between the changes in inhibitory control performance and event-related cortical oscillations during each stimulation condition. Together, these aims progress our knowledge of how STN DBS disrupts cognitive processes like inhibitory control and the relationship between stimulation frequency and the neurophysiological mechanisms behind this disruption. Insight into these neurophysiological mechanisms will improve the efficacy of STN DBS as novel stimulation paradigms and technologies for implementing STN DBS are being developed.
Even though studies have repeatedly reported that subthalamic nucleus deep brain stimulation impairs the control of inhibitory actions in people with Parkinson?s disease, such as stopping a planned movement, the mechanism of this impairment is unknown. It is also unknown whether changes in stimulation frequency can reduce this impairment. The proposed research will determine the effect of stimulation and stimulation frequency on inhibitory control performance, and the associated cortical oscillatory activity, in order to provide insights into the neurophysiological mechanisms related to deep brain stimulation that adversely affect inhibitory control.
