Dopamine depletion can be predicted by the aperiodic component of subthalamic local field potentials

Abstract

Electrophysiological biomarkers reflecting the pathological activities in the basal ganglia are essential to gain an etiological understanding of Parkinson’s disease (PD) and develop a method of diagnosing and treating the disease. Previous studies that explored electrophysiological biomarkers in PD have focused mainly on oscillatory or periodic activities such as beta and gamma oscillations. Emerging evidence has suggested that the nonoscillatory, aperiodic component reflects the firing rate and synaptic current changes corresponding to cognitive and pathological states. Nevertheless, it has never been thoroughly examined whether the aperiodic component can be used as a biomarker that reflects pathological activities in the basal ganglia in PD. In this study, we examined the parameters of the aperiodic component and tested its practicality as an electrophysiological biomarker of pathological activity in PD. We found that a set of aperiodic parameters, aperiodic offset and exponent, were significantly decreased by the nigrostriatal lesion. To further prove the usefulness of the parameters as biomarkers, acute levodopa treatment reverted the aperiodic offset. We then compared the aperiodic parameters with a previously established periodic biomarker of PD, beta frequency oscillation. We found a significantly low negative correlation with beta power. We showed that the performance of the machine learning-based prediction of pathological activities in the basal ganglia can be improved by using the lowly correlated parameters, beta power and aperiodic component. We suggest that the aperiodic component will provide a more sensitive measurement to early diagnosis PD and have the potential to use as the feedback parameter for the adaptive deep brain stimulation.

A sagittal gradient of pathological and compensatory effects of neurophysiological slowing in Parkinson’s disease

“…This has led to a hypothesized slowing of brain activity in patients with PD, but it remains unclear whether such a neurophysiological effect relates to clinical features of the disease, and whether any such relationships are of a deleterious or compensatory nature. These multi-spectral deviations from healthy levels also comprise rhythmic and/or arrhythmic components 43-46 , for which clinical interpretation and significance for frequency-specific neuromodulation therapies remain to be established in PD 19,42,47-51 .…”

The neurophysiological brain-fingerprint of Parkinson’s disease

“…Recent studies have shown alterations of arhythmic brain activity in PD patients 12,67,68 . Here we show that the arhythmic component of the neurophysiological spectrum can differentiate between individuals and contributes to the association between inter-individual differentiability and motor symptoms.…”