Sensorimotor Frequency Tagging Is Enhanced by Auditory and Audiovisual but Not Visual, Inputs During a Body-Walking Task.

Body movements like walking can synchronize with auditory and visual inputs presented within a periodic frequency range, peaking around 2 Hz. Some evidence has shown that the spontaneous tempo of human locomotion is around 2 Hz. The EEG frequency-tagging approach allows us to capture the coupling of beat perception with neural brain oscillations at beat frequency. This study used EEG frequency tagging to explore brain dynamics during the perception of walking-related sensory information in the auditory (footstep sounds) and visual (point-light figure) modalities. Sensory inputs were delivered at different rates (1, 2, and 3.6 Hz) in rhythmic or random sequences while recording EEG activity. The experiment included three conditions: (i) auditory, (ii) visual, and (iii) audiovisual, including data from 22 participants. Results showed a main effect of rhythmic sequences compared with random sequences across all frequencies in all three auditory, visual, or audiovisual conditions. Specifically, at 2 Hz, rhythmic sequences enhanced neural entrainment in the sensorimotor cortex for auditory and audiovisual conditions. This effect was absent in the visual condition alone. Notably, 2 Hz rhythmic sequences in the audiovisual condition led to coupling with temporal, sensorimotor, and occipital regions. The study suggests that sensory auditory input related to walking movement presented at 2 Hz can mediate neural entrainment with sensorimotor areas. The findings of this study can have an impact on the spontaneous rhythmic integration of body movements using sensory inputs for walking rehabilitation.