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Modulation of human corticomuscular beta-range coherence with low-level static forces


Dr R. Kristeva or Dr Matthias Witte, as above.
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Although corticomuscular synchronization in the beta range (15–30 Hz) was shown to occur during weak steady-state contractions, an examination of low-level forces around 10% of the maximum voluntary contraction (MVC) is still missing. We addressed this question by investigating coherence between electroencephalogram (EEG) and electromyogram (EMG) as well as cortical spectral power during a visuomotor task. Eight healthy right-handed subjects compensated isometrically static forces at a level of 4% and 16% of MVC with their right index finger. While 4% MVC was accompanied by low coherence values in the middle to high beta frequency range (25–30 Hz), a significant increase of coherence mainly confined to low beta frequencies (19–20 Hz) was observed with force of 16% MVC. Furthermore, this increase was associated with better performance, as reflected in decreased relative error in force during 16% MVC. We additionally show that periods of good motor performance within each condition were associated with higher values of EEG–EMG coherence and spectral power. In conclusion, our results suggest a role for beta-range corticomuscular coherence in effective sensorimotor integration, thus stabilizing corticospinal communication.