Does walking influence how people process sensory information, like sounds, from the environment? In a new JNeurosci paper, researchers led by Liyu Cao, from Zhejiang University, and Barbara Händel, from University of Würzburg, explored whether walking direction influences how people process sounds.
Thirty volunteers walked in an eight-shaped path as they listened to a continuous stream of sound with changing intensities while researchers collected recordings of brain activity. People had stronger neural responses to sound while walking as opposed to standing or walking in place. These responses changed to the same degree as manipulations to sound intensity. Notably, different walking directions changed how the brain responded to sound. Cao provides an example, "When people made a right turn, responses to sounds from the right ear were enhanced at the beginning of the turn and then suppressed, relative to the responses to sounds from left. This could reflect a change in attention during turns."
When the authors introduced bursts of tones into the sound stream, these tones disrupted the brain's associative response and elicited a different response. As before, this response was strongest during walking, but only when the sound bursts happened in one ear as opposed to both ears. This finding suggests that neural responses may be particularly sensitive to auditory input from the periphery when people are walking
Bridging the findings together, says Cao, "This could reflect a filtering operation of the brain: It might actively suppress predictable background sounds—like our own footsteps—while increasing sensitivity to unexpected sounds from the side. This might allow for faster reaction times and safer navigation in dynamic environments. It could also suggest that our auditory system appears to be optimized for detecting novelty and deviation during movement."
