Frequency-specific and spatiotemporal dynamics of β-γ phase-amplitude coupling in Parkinson's disease.
High-density EEG with source localization reveals a frequency-specific increase in high beta (23–35 Hz)-gamma phase–amplitude coupling across the cortical motor network in Parkinson's disease that correlates with bradykinesia and rigidity (but not tremor) and is reduced by dopaminergic medication…
What the AI sees
High-density EEG with source localization reveals a frequency-specific increase in high beta (23–35 Hz)-gamma phase–amplitude coupling across the cortical motor network in Parkinson's disease that correlates with bradykinesia and rigidity (but not tremor) and is reduced by dopaminergic medication…
Research significance
This identifies a symptom-linked, medication-responsive electrophysiological biomarker and a frequency- and region-specific target for tuning invasive or noninvasive neuromodulation (e.g., DBS or closed-loop stimulation), improving translational precision for PD circuit-based therapies.
Source abstract
Cross-frequency coupling (CFC) has been proposed to facilitate neural information transfer across spatial and temporal scales. Phase-amplitude coupling (PAC), a type of CFC in which the amplitude of a faster brain oscillation is coupled to the phase of a slower brain oscillation, is implicated in various higher-order cognitive functions and was shown to be pathologically altered in neurological and psychiatric disease. In Parkinson's disease (PD), the coupling between gamma amplitude (50-150 Hz) and beta phase (13-35 Hz) is exaggerated. Enhanced β-γ PAC was found in the subthalamic nucleus and various cortical sources and shown to be responsive to dopaminergic therapy and deep brain stimulation (DBS). Therefore, exaggerated β-γ PAC has been proposed to be a disease marker and a potential target for brain circuit interventions. Despite these promising findings, a significant knowledge gap remains, as the spatial and frequency-specific dynamics of β-γ PAC and its association with motor symptoms and therapy remain elusive. To address this knowledge gap, we employed high-density electroencephalography (EEG) with source localisation techniques for patients with PD at rest. We highlight three key findings: (1) a frequency-specific increase in high β (23-35 Hz)-γ PAC within and between sources of the cortical motor network, (2) a link between elevated high β-γ PAC and bradykinesia and rigidity when OFF medication, but not tremor, and (3) a medication-induced reduction in high β-γ PAC in the supplementary motor area correlating with clinical improvement. Altogether, this study provides novel insights into the pathophysiology of PD as an oscillopathy and identifies high β-γ PAC as a potential marker of Parkinsonian symptoms and treatment effects. This has important implications for invasive as well as non-invasive therapeutic strategies as high β-γ PAC targeting might hold greater promise than targeting β-γ PAC per se.