Fig. 7: The DBS can be tuned to provide maximum modulatory effect based on the phase of ECA waveform.

a The ECA waveforms after 22 s of low-frequency stimulation from the six subjects with both 20 Hz and high-frequency stimulation experiments. The location of the red circles denotes where the next 130, 160, and 180 Hz stimulation pulses would be, if the stimulation continued with the specified frequency. The size of the circle denotes the relative amplitude of the induced HFO by that stimulation. b The information in a is presented on polar coordinates to illustrate the phase preference. The arrow length denotes the relative amplitude of the induced HFO power. The mean angle was 265° and is denoted by the red line. The preferred phase was between 189° and 338° (n = 6) and is denoted by the highlighted background. c A pendulum and a representative ECA waveform to illustrate the swing-like behavior of the evoked response. The shaded region illustrates the preferred phase angles from panel b. The timings of 130, 160, and 180 Hz stimulus pulses are marked as well. When the next stimulation pulse is at a preferred phase location (forward motion, green), the modulatory effects can be enhanced. On the other hand, stimulating at the other phase (backward motion, red) could hinder effect of DBS.