Introduction: Subthalamic Nucleus (STN) Local Field Potentials (LFP) are considered the most informative feedback signal for a closed-loop deep brain stimulation (DBS) system. Traditionally, data collection of STN-LFP in humans has been restricted to the operating room during DBS implantation.
Methods: We use the Medtronic Activa PC+S system to record STN-LFP in the clinic to determine the reliability of the STN-LFP over time and assess dynamics of the STN-LFP with behavior and dopaminergic medication. Six subjects were implanted with the PC+S system. Bilateral STN-LFP recordings were performed in the operating room and in the clinic at one, three, six, and twelve months after implant. Subjects were cued to perform voluntary behaviors including left and right hand movement, left and right arm movement, mouth movement, and speech.
Results: We observed inter-subject variability that led us to focus on intra-subject analysis. STN-LFP movement related power changes in Beta (13-30Hz) and Gamma (40-70Hz) frequency bands were consistent across multiple recordings. The STN-LFP recorded with the PC+S demonstrated movement-modulated desynchronization of beta frequency and synchronization of gamma frequency oscillations. Medication did not diminish the magnitude of the beta frequency oscillatory desynchronization with movement. However, movement related gamma frequency band oscillatory synchronization was only observed in the medication on state.
Conclusions: These findings demonstrate that the PC+S system provides robust STN-LFP recordings in ambulatory patients, allowing for these signals to be recorded in settings that better represent the real-world in a variety of medication states. These results suggest oscillatory power in beta and gamma frequency bands of STN-LFP modulates with movement and medication state. Consistent with the literature, synchronization of gamma frequency oscillatory power was only observed in the medication on state, whereas desynchronization of beta frequency oscillations was readily observed in both the medication off and on state.
Patient Care: This research explores the dynamics of Subthalamic Nucleus (STN) Local Field Potentials (LFP) with behavior and dopaminergic medication. Reliability of STN LFP signals is important as it may be used as a feedback signal for future closed-loop deep brain stimulation (DBS) systems. Closed-loop DBS has the potential to maximize PD therapy, minimize potential side effects, and extend the battery life of the system.
Learning Objectives: By the conclusion of this session, participants should be able to: 1) Describe STN-LFP patterns with motor and language behaviors, 2) Discuss how dopaminergic medication alters STN-LFP patterns of activity.