The Effect of Cue Frequency, Modality and Rhythmicity on Finger Tapping Behaviour and Movement-Related Cortical Activity.

Sensorimotor synchronization (SMS) involves the coordination of movements with rhythmic sensory cues. While cue characteristics influence SMS behaviour and neural pathways, their impact on cortical activity beyond motor areas is less understood. This exploratory EEG study examined how various cue characteristics, including cue frequency, modality and rhythmicity, influence behaviour and movement-related cortical activity in (non-)motor areas during SMS. Seventeen healthy participants performed finger tapping with cues varying in frequency (slow: 1 Hz, fast: 3.2 Hz), modality (visual, auditory) and rhythmicity (isorhythmic, polyrhythmic). SMS behaviour and movement-related beta power were evaluated. Key findings include the following: (1) Increasing cue frequency, and therefore movement speed, reduced tap accuracy, especially with visual cues. Slow cues induced strong beta suppression followed by beta rebound after the tap in the contralateral sensorimotor cortex, while fast cues induced a weaker but sustained beta suppression. (2) Auditory cues enabled more accurate tap behaviour and induced stronger beta suppression in the contralateral premotor cortex compared to visual cues. (3) Polyrhythmic auditory cues delayed taps compared to isorhythmic cues, although tap accuracy was similar. Isorhythmic cues enhanced frontoparietal beta power, whereas polyrhythmic cues showed widespread right-hemispheric beta suppression. Findings suggest discrete and continuous movement processing with slow and fast cues, respectively. Auditory cues offer more sensory guidance, especially at higher frequencies. Endogenous, top-down control with isorhythmic cues may switch towards stimulus-driven, bottom-up control with auditory polyrhythmic cues. Overall, our findings highlight how cue characteristics shape motor behaviour and neural processes, suggesting distinct movement control strategies depending on frequency, modality and rhythmicity.