Frequency tagging in the sensorimotor cortex is enhanced by footstep sounds compared to visual information movement in a walking movement integration task

Aim: To investigate brain dynamics supporting rhythmic sensorimotor synchronization when coupling auditory and visual inputs related to walking movement using an EEG-frequency tagging approach. To investigate whether visual, audio, and audiovisual input related to walking movement may induce brain connectivity coupling between different brain areas. Methods: We used a mixed-model study design presenting both auditory (footstep sound) and visual (walking point-light-figure) inputs. Sensory inputs were presented at different frequency rates (1 Hz, 2 Hz, 3.6 Hz) in a rhythmic or random sequence while recording EEG activity using a frequency tagging approach, in three different experimental blocks: (i) Auditory block; (ii) Visual block; (iii) Audiovisual block. Each auditory, visual, or audiovisual stimulus lasted sixty seconds. Experimental blocks were presented in a counterbalanced order among the participants. Results: 22 participants were analyzed. We found a main effect of rhythmic compared to random sequences at all frequencies in all conditions. At 2Hz the effect of Rhythm was present in the audio condition in both sensorimotor (p < 0.0001) and temporal (p < 0.0001) ROIs. Also, in audiovisual condition, the effect of Rhythm was present in the sensorimotor (p < 0.0001), temporal (p < 0.0001), and occipital (p < 0.0001) ROIs. In visual condition, the effect of rhythm was present in the occipital ROI at 2 and 3.6 Hz (p < 0.0001). Conclusions: Rhythmic sequences induce greater frequency tagging effect in the selected brain areas. 2Hz rhythmic sequences in both audio and audiovisual condition induces higher synchronization coupling in the sensorimotor and temporal ROIs.