Cortical beta coherence provides a stronger non-invasive predictor of movement vigor than local beta power

Background: Movement elicits a robust decrease in motor cortical beta-band (β ; 13-30 Hz) power contralateral to the moving limb. On this basis, studies have targeted contralateral motor cortical β power to decode or modulate movement vigor (initiation and execution speed) non-invasively. Yet, reported behavioral effects and decoding accuracy remain modest. Considering that controlling vigor involves distributed brain regions, network-level metrics that capture interactions between cortical regions may track changes in vigor more accurately than local power. We therefore tested whether β cortico-cortical coherence, measured as functional connectivity between contralateral motor cortex and other cortical areas, predicts movement vigor more reliably than β power. Methods: Thirty healthy participants performed right hand opening at two instructed speeds (Fast, Slow), while high-density electroencephalography (EEG) was recorded. EEG data were source-localized, and analyses were conducted at the sensor and source levels. We compared β power and β coherence in their ability to discriminate Fast from Slow condition. Effects were assessed across the whole scalp/cortex and using subject-specific selections of electrodes/parcels optimized for discrimination. Results: Fast trials exhibited shorter movement time (MT) and reaction time (RT) than Slow trials, indicating higher vigor. No electrodes cluster showed any significant β power difference between Fast and Slow conditions. With subject-specific channel selection, β power discriminated vigor above chance in most participants, but the polarity of the β power contrast (Fast < Slow or Fast > Slow) varied across individuals. In contrast, with subject-specific parcel selection, β coherence was consistently reduced during Fast relative to Slow in the majority of participants. Across participants, lower β coherence, but not β power, was significantly associated with larger Slow-Fast vigor difference. Conclusions: β cortico-cortical coherence between contralateral motor cortex and other cortical regions provided a more robust and consistent predictor of movement vigor than contralateral motor cortical β power. β coherence exhibited a sustained reduction during fast movements across trials and participants, supporting its use as target for non-invasive neuromodulation of vigor and as feature for decoding intended movement speed.