L-Dopa-induced changes in aperiodic bursts dynamics relate to individual clinical improvement in Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative disease characterized by severe motor symptoms, transiently alleviated by medication (e.g. levodopa), and widespread brain activity alterations that remain poorly understood at a large scale level. To address this issue, we used resting-state STN-DBS and motor EEG data from 11 PD patients before and after levodopa treatment. Neuronal avalanches, i.e., brief, widespread bursts of activities, were detected and compared across the two conditions. Interestingly, we noted shorter and smaller avalanches in the OFF-condition and fewer, longer, and larger avalanches in the ON-condition. We then computed the avalanche transition matrices to track the contact-wise patterns of avalanche spread. We found a significantly higher probability of avalanche spread within and between the STN and motor cortex in the ON-condition. Furthermore, increased propagation of avalanches correlated with clinical improvement. Our study identifies potential biomarkers for electrophysiological changes in PD through cross-modality assessment of aperiodic activities.