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

backgroundMovement 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.

methodsThirty 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.

resultsFast trials exhibited shorter movement time and reaction time than Slow trials, indicating higher vigor. No electrodes cluster showed any significant β power difference between Fast and Slow conditions. With subject-specific channels selection, β power discriminated vigor above chance (ΔAUC = 0.15, p = 10− 15), but no consistent sign of β power contrast (Fast < Slow or Fast > Slow) was found across participants (t = 0.43, p = 0.673). In contrast, using subject-specific parcels selection, β coherence was reduced during Fast relative to Slow in the majority of participants (t = − 2.32, p = 0.028) and predicted speed condition above chance (ΔAUC = 0.15, p = 10− 18). Across participants, lower β coherence (r = − 0.33, p = 0.038), but not β power (r = − 0.11, p = 0.286), was significantly associated with larger Slow-Fast vigor difference.

conclusionsβ 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.