LAUSR

s Brain Stimulation 14 (2021) 1589e1707 frequency (~300 Hz) oscillations in GP and STN. This evoked activity resembled a sinusoid, growing in the shape of a sigmoid throughout the burst, and decaying exponentially after the last burst stimulation. This novel sigmoid-exponential-sinusoid (SES) model successfully fit the data with R-squared values of up to 0.9. Theories of the origin of this phenomenon involve local patterns of inhibition and excitation in STN, or interactions between STN and connected structures, such as the pallidum. Our detected high-frequency oscillations in STN and GP from pallidal stimulation, complementing those previously observed from STN stimulation, support the hypothesis that the phenomenon is generated by a loop involving both structures. No oscillatory response was detected when stimulating or recording in thalamus. This implies that the phenomenon is likely unique to BG, making it a promising biomarker. It has also been suggested as a possible feedback signal for closed-loop DBS, which our SES model parameters provide convenient quantitative measurements for. Finally, our findings in a dystonic patient imply that this phenomenon is not unique to Parkinson’s disease, but likely generalizable to other movement disorders and perhaps even healthy subjects.