Different features of the cortical sensorimotor rhythms are uniquely linked to the severity of specific symptoms in Parkinson's disease

Parkinsons disease (PD) is associated with changes in neural activity in the sensorimotor alpha and beta bands. Using magnetoencephalography (MEG), we investigated the role of spontaneous neuronal activity within the somatosensory cortex in a large cohort of early-to mid-stage PD patients (N = 78) and age- and sex matched healthy controls (N = 60) using source reconstructed resting-state MEG. We quantified features of the time series data in terms of oscillatory alpha power, beta power, and 1/f broadband characteristics using power spectral density, and also characterised transient beta burst events in the time-domain signals. We examined the relationship between these signal features and the patients disease state, symptom severity, age, sex, and cortical thickness. PD patients and healthy controls differed on PSD broadband characteristics, with PD patients showing a steeper 1/f exponential slope and higher 1/f offset. PD patients further showed a steeper age-related decrease in the burst rate. Out of all the signal features of the sensorimotor activity, only burst rate was associated with increased severity of bradykinesia. Our study shows that general non-oscillatory features (broadband PSD slope and offset) of the sensorimotor signals are related to disease state and oscillatory burst rate scales with symptom severity in PD.