Voluntary action sharpens sensory prediction and facilitates neural processing of contingent sensory stimuli
Self- and externally generated sensations differ in sensory responses and motor preparation. However, mechanistic evidence linking the two is scarce. Here, participants made active (self-initiated) or passive (finger moved by electromagnet) movements that triggered a bimodal auditory/visual stimulus. These were followed, in a block-wise manner, by a unimodal auditory/visual comparison stimulus, and participants judged which stimulus was brighter or louder. Motor preparation ERPs encoded task modality and movement, while sensory ERPs showed reduced task differences for active, demonstrating sensory suppression. Next, we decoded task modality within active and passive. During motor preparation, the active condition showed higher accuracy, reflecting enhanced predictive processes. In the sensory perception period, accuracy was higher in the passive condition, mirroring previous reports of reduced sensory responses to self-generated stimuli. Temporal generalisation showed pattern similarities in the alpha band amplitude between the motor preparation and the stimulus perception windows. This suggests that alpha oscillations may encode sensory predictions generated during motor preparation. Our findings provide mechanistic evidence of action-effect prediction during voluntary actions.