%0 Journal Article
%A Scholten, Marlieke
%A Schoellmann, Anna
%A Ramos-Murguialday, Ander
%A López-Larraz, Eduardo
%A Gharabaghi, Alireza
%A Weiss, Daniel
%T Transitions between repetitive tapping and upper limb freezing show impaired movement-related beta band modulation
%D 2020
%@ 1388-2457
%U https://hdl.handle.net/11556/3528
%X Objective: Freezing phenomena in idiopathic Parkinson's disease (PD) constitute an important unaddressed therapeutic need. Changes in cortical neurophysiological signatures may precede a single freezing episode and indicate the evolution of abnormal motor network processes. Here, we hypothesize that the movement-related power modulation in the beta-band observed during regular finger tapping, deteriorates in the transition period before upper limb freezing (ULF). Methods: We analyzed a 36-channel EEG of 13 patients with PD during self-paced repetitive tapping of the right index finger. In offline analysis, we compared the transition period immediately before ULF (‘transition’) with regular tapping regarding movement-related power modulation and interregional phase synchronization. Results: From time-frequency analyses, we observed that the tap cycle related beta-band power modulation over the left sensorimotor area was diminished in the transition period before ULF. Furthermore, increased beta-band power was observed in the transition period compared to regular tapping centered over the left centro-parietal and right frontal areas. Phase synchronization between the left fronto-parietal areas and the left sensorimotor area was elevated during transition compared to regular tapping. Conclusion: Together, these results indicate that diminished beta band power modulation and increased phase synchronization precede ULF. Significance: We demonstrate that pathological cortical motor processing is present in the transition phase from regular tapping to an ULF episode.
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