ETD

• basal ganglia
• EEG
• functional and effective connectivity
• Granger causality.
• imaginary coherence
• Parkinson’s disease
• reach-to-grasp
• STN local field potentials

This thesis investigates cortical–subcortical communication in Parkinson’s disease (PD) by analysing simultaneous cortical electroencephalographic signals (EEG) and subthalamic nucleus (STN) local field potentials (LFPs) recorded during reach-to-grasp movements in PD patients. The aim was to characterize how interactions within and among networks in the motor control circuits are dynamically modulated in pathological conditions across distinct motor phases using a combination of spectral, functional and effective connectivity analyses.
Data-driven spectral analyses revealed robust task-related modulations predominantly in the beta frequency range ([13-30] Hz) across both cortical and subcortical signals. Crucially, this is also the band known to be pathologically synchronized in the basal ganglia of PD patients. Functional connectivity analysis identified a stable high-beta (>20 Hz) coupling between cortex and STN across motor phases, while directed connectivity measures revealed a dynamic cortical-to-STN information flow that was selectively reduced during the grasp phase.
Together, these findings provide a multilevel characterization of phase-specific oscillatory interactions within cortical–basal ganglia networks, highlighting how pathological beta-band communication is differentially engaged during distinct components of goal-directed motor behaviour in PD.