Space and Time Frequency-Dependent Interactions in Subthalamic Nucleus Local Field Potentials in Parkinson's Disease

Parkinson’s disease (PD) is the second most common neurodegenerative disorder in the US, with a prevalence of 1% in the population over 60 years old and an annual economic impact estimated in 23 billion dollars in direct costs only. Deep Brain Stimulation (DBS) is an effective surgical treatment for advanced PD in patients who developed a resistance to the pharmacological medication. DBS procedure allows the recording of electrophysiological signals known as Local Field Potentials (LFP) from deep brain structures such as the Subthalamic Nucleus (STN). LFP represent the synchronized activity of a relatively large population of neurons and have been shown to correlate with many PD symptoms and contribute with their use to the success of DBS practice. However, the pathophysiology of PD remains unclear. In this work, long-term STN LFP recordings of ten PD patients were analyzed using classical as well as recently developed methods to investigate: (i) the spatial distribution of spectral activity and nonlinear cross-frequency coupling in the STN in medicated and unmedicated conditions, (ii) the pattern of spectral changes following medication intake, and (iii) the correlation of features extracted from LFP with clinical scores and sensory data during resting state and movement execution. The main findings showed that cross-frequency coupling is stronger in the superior part of STN and that the timings of changes in LFP spectral power after pharmacological treatment are frequency-dependent. The results support and integrate existing evidence that LFP analysis may assist in the target localization during DBS surgery and contribute to the development of smarter algorithms for next generation closed-loop DBS applications.Computer Science, Department o