Readiness potential in human functional magnetic resonance imaging motor task data

The readiness potential (RP), also known as the Bereichtschaftspotential, is commonly observed in EEG recordings as a slow build-up of negative electrical potential prior to self-directed motor movements (Kornhuber et al. 1965). In this study, we analyzed motor task-based functional magnetic resonance (fMRI) data acquired from 262 human participants, focusing on the degree of signal phase synchronization across different frequency spans and brain regions. A new method that clusters brain regions based on instantaneous phase allowed for time resolved estimation of cross-subject phase synchronization. We show that during rest periods that precede movement, an fMRI equivalent of the RP is gradually established in a network that encompasses the bilateral supplementary motor area and parts of the cingulo-opercular network, recently described as the brain's Action Mode network (Dosenbach et al. 2025). Importantly, an anticipatory negative shift in the fMRI signal was observed in both single subjects and single epochs. Tongue movement elicited strong synchronization between the orbitofrontal, ventromedial, and temporal pole cortices. Our findings suggest a link between fMRI and electrophysiological recordings of anticipatory motor events in the brain. The method presented here grades brain synchronization along an in-phase and anti-phase continuum and has applications in clinical settings, as well as for cognitive brain mapping that goes beyond anticipation.