Embodied neural synchrony to rhythmic structure: An ERP and frequency-domain investigation of beat entrainment

Neural entrainment-the alignment of endogenous oscillations to the temporal structure of external stimuli-facilitates temporal prediction and enhances sensory processing. We investigated how audiovisual rhythmic stimuli at distinct frequencies modulate EEG dynamics and event-related potentials (ERPs) in 29 healthy adults. Participants observed 110 video-recorded finger-tapping sequences, categorized as low-frequency (~3.49 Hz) or high-frequency (~6.65 Hz), while 128-channel EEG was recorded. ERPs revealed larger late positive potentials for the latter than the former, with centroparietal maxima, and a right-hemisphere dominance for low-frequency rhythms. EEG spectral analyses performed within the 0.5-30 Hz range showed decreased delta power and increased alpha power during fast versus slow stimulation. Morlet wavelet analysis confirmed frequency-specific entrainment, with alpha-band increases over premotor and sensorimotor areas during high-frequency tapping. Neural entrainment analyses revealed a higher Weighted Entrainment Power Index (WEPI) for low- (3.95) compared to high-frequency stimuli (2.80), indicating stronger alignment of EEG power with slower rhythmic inputs. Consistently, the Entrainment Intensity Index (EII = 0.53 μV2/Hz) quantified a robust frequency-dependent modulation of spectral power across delta, theta, and alpha bands. Collectively, these results demonstrate selective neural entrainment to movement-sound coupling, reflected in both ERP amplitudes and EEG oscillatory power, and highlight the role of sensorimotor networks in processing temporal structure of actions.