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. Author manuscript; available in PMC: 2014 Sep 15.
Published in final edited form as: Mov Disord. 2013 Sep 15;28(11):1544–1551. doi: 10.1002/mds.25684

Figure 4.

Figure 4

Power Spectral Densities (PSD) and Frequency Ratios of anteroposterior shank acceleration during a 2-min 360° turn-in-place. The PSD shows that most of the power of leg motion during healthy turning is below 2 Hz, with more high frequencies represented in patients with PD, especially in patients with PD who have freezing of gait (FoG+), The Frequency rations is the power at 3–8Hz/ power at 0.5–3Hz). The higher frequencies represent “trembling in place” and the lower frequencies the stepping movements. From the top to bottom: healthy control subject, a PD subject with freezing of gait OFF medication and a PD subject with similar Motor UPDRS scores, without freezing of gait OFF medication.