Walking modulates active auditory sensing.

Walking provides the motor foundation for navigation, while navigation ensures that walking is purposeful and adaptive to environmental contexts. Sensory processing of environmental information acts as the informational bridge that connects walking and adaptive navigation. In the current study, we assessed if walking and the walking direction influences neuronal dynamics underlying environmental information processing. To this end, we conducted two experiments with 12 male and 18 female participants while they walked along an 8-shaped path. Auditory entrainment stimuli were continuously presented, and mobile EEG (electroencephalogram) was recorded. We found increased auditory entrainment (auditory steady-state response) and early auditory evoked responses during walking compared to standing or stepping-in-place. We also replicated the well-established reduction of occipital alpha power during walking. The increase of auditory entrainment and the decrease of alpha power were correlated across participants. In the second experiment, randomly presented transient burst tones led to a perturbation of the auditory entrainment response. The perturbation response was stronger during walking compared to standing, however, only when the burst tones were presented to one ear but not to both ears. Most importantly, we found that the auditory entrainment was systematically modulated dependent on the walking path. The entrainment responses changed as a function of the turning direction. In general, the current work shows that walking changes auditory processing in a walking path-dependent way which might serve to optimize navigation. The walking path related modulation might further reflect a shift of attention, marking a form of higher-order active sensing.Significance Statement In this mobile EEG walking study, we uncovered a dynamic shift in auditory attention that aligns with changes in walking trajectory. Specifically, during turns, the brain prioritizes auditory input from the side of turn direction before the turn apex, then shifts preference to the opposite side. These findings reveal an active sensing mechanism that goes beyond simple motor adjustments to adjust sensory input but suggests that the brain dynamically optimizes the processing of sensory input e.g. to facilitate navigation. This study offers potential applications for understanding spatial awareness in real-world environments and improving navigational aids.