Alpha and beta cortico-motor synchronization shape visuomotor control on a single-trial basis
A central question in sensorimotor neuroscience is how sensory inputs are mapped onto motor outputs to enable swift and accurate responses, even in the face of unexpected environmental changes. In this study, we leverage cortico-motor phase synchronization as a window into the dynamics of sensorimotor loops and explore how it relates to online visuomotor control. We recorded brain activity using electroencephalography (EEG) while participants performed an isometric tracking task that involved transient, unpredictable visual perturbations. Our results show that synchronization between cortical activity and motor output (force) in the alpha band (8-13 Hz) is associated with faster motor responses, while beta-band synchronization (18-30 Hz) promotes more accurate control, which is in turn linked to a higher likelihood of obtaining rewards. Both effects are most pronounced immediately before perturbation onset, underscoring the predictive value of cortico-motor phase synchronization for sensorimotor performance. Single-trial analyses further reveal that deviations from the preferred cortico-motor phase relationship are associated with longer reaction times and larger errors, and these phase effects are independent of power effects. Thus, beta-band synchronization may reflect a cautious, reward-oriented control strategy, while alpha-band synchronization enables quicker, though not necessarily efficient, motor responses, indicating a complementary, more reactive control mode. These results highlight the finely tuned nature of sensorimotor control, where different aspects of sensory-to-motor transformations are governed by frequency-specific neural synchronization on a moment-to-moment basis. By linking neural dynamics to motor output, this study sheds light on the spectrotemporal organization of sensorimotor networks and their distinct contribution to goal-directed behavior.