Figure 1

Division of the recorded angular velocity signal from the hand of one of the patients during the action tremor test (setting DBS80%), into tremor and non-tremor windows. A) A segment of 13 seconds of the angular velocity signals (blue: pitch, green: roll, and red: yaw) divided into an action tremor component (upper graph) and a tapping component (lower graph). The tremor component and tapping component are visualized by filtering the recorded signal: a band pass filter (4th order non-causal Butterworth filter, pass band 3.6-7.5 Hz) was used to retrieve the tremor component; filtering the signal with a low pass filter (4th order non-causal Butterworth filter with a cut off frequency of 3.4 Hz) revealed the tapping component. Classification of the 3-second windows into tremor (T) and non-tremor (NT) is indicated. B) Upper graph: the average power spectral density of all 3-second windows classified as tremor windows (blue line) and non-tremor windows (red line). The double peak in the power spectral density of the tremor windows expresses the variation in tremor frequency with time. Lower graph: the PSD of each 3-second window classified as tremor (blue line) or non-tremor (red line) window.