Axis-specific neuro-musculoskeletal contributions to postural stability and vibration avoidance in mice

Abstract

Animals must appropriately regulate their responses to external mechanical oscillations such as whole-body (WB) vibration to ensure postural stability. However, knowledge of mouse responses to WB vibration remains limited. Here, we used high-speed video-based quantitative analyses to characterize body-part movements in awake and anesthetized mice under vertical, longitudinal, and lateral WB vibration. Awake mice exhibited lower resonance frequencies and smaller displacement amplitudes than anesthetized mice during vertical and lateral WB vibration, but not longitudinal vibration, indicating that the neuro-musculoskeletal (NMS) system contributes to postural stability in a vibration axis-dependent manner. Vibration modeling suggests that the NMS system acts as an active vibration absorber by reducing effective stiffness and dynamically adjusting effective damping, analogous to active vehicle suspensions. Axis-specific vibration control may reflect an evolutionary balance between postural stability and locomotor efficiency in quadrupeds, paralleling the design principles of rear-wheel-drive vehicles. Behavioral preference tests revealed that mice selectively avoid vertical WB vibration at specific frequencies, but neither lateral nor longitudinal WB vibration. These findings reveal an axis-specific NMS control principle analogous to vehicle design, linking postural regulation, locomotor efficiency and avoidance behavior, and advancing our understanding of the biomechanics and behavior of quadrupeds exposed to WB vibration.