Reactivity of the Autonomic Nervous System During Visual-Physical Incongruent Walking Conditions-A Virtual Reality Study

The force of gravity critically impacts locomotion regulation while walking on inclined surfaces. To construct an updated assessment about the gravitational consequences and change gait patterns accordingly, the central nervous system (CNS) integrates multiple sensorial cues, including vestibular and proprioceptive (i.e., body-based cues) and visual. Not much is known about the contribution of the autonomic nervous system (ANS) to locomotion regulation, especially when multiple types of sensorial cues are involved. Here we examine the responsiveness of the ANS, as reflected by cardiac reactivity, for example heart rate (HR) and heart rate variability (HRV), to coherent versus non-coherent sensorimotor signaling. Fourteen healthy young participants completed level, uphill, and downhill self-paced walking trials in a virtual reality (VR) environment in which the incline of the visual scene was either congruent or incongruent with the physical incline of the walking surface. We found that during level walking, incongruent visual cues (i.e., up/downhill scenery) triggered alterations in ANS balance, reflected in HRV decrease and in a residual increase of HR. Taken together with the fact that an ultimate change in gait patterns requires alterations in cardiac resources, we speculate that ANS function and its responsive modes of action are, in fact, facilitating adaptive behavior.