An exemplar effect of subthalamic stimulation at fT in a patient with Parkinson’s disease. (A) Median tremor frequency remained unchanged at 4.6 Hz during stimulation at 4 Hz. (B) Tremor phase was pulled to a region extending from 180 to 240° indicating significant tremor entrainment during stimulation. Tremor phase when stimulation was switched off was uniformly distributed around the unit circle. Outer circle corresponds to tremor phase likelihood of 0.1, while the inner circle corresponds to tremor phase likelihood of 0.05. (C) Tremor amplitude was not modulated depending on the timing of stimulation pulses with respect to the tremor cycle. Significance of tremor phase dependent tremor amplitude modulation was assessed with respect to instantaneous tremor amplitude variability when stimulation was switched off using the Wilcoxon rank sum test and significance levels corrected for multiple comparisons using the false discovery rate procedure. Circles show median change in tremor amplitude and shaded regions indicate the 95th confidence intervals of the median values.
