Sensory information for control of gait stability

Bipedal locomotion requires active control in the frontal plane, which is accomplished mainly be adjusting foot placement based on the kinematics of the body center of mass (COM) in the preceding step. This however triggers the question how the brain can estimate COM kinematics from sensory information. We propose that a weighted combination of visual, vestibular and proprioceptive information is used. While manipulations of these three sources of information have shown effects on motor responses during walking that were phase-dependent and scaled according to the reliability of the inputs, the relevance of these responses for balance control remains unclear. Here we take the unique approach to quantify balance responses based on individualized models of balance control, with the COM kinematics during swing predicting the subsequent foot placement location during unperturbed gait. Adjustments of foot placement relative to the model predictions upon application of sensory manipulations quantify balance responses to sensory input. This will allow us to compare sensory weighting between standing and walking, between phases of the gait cycle and to study reweighting of the sensory modalities when one of the three is rendered unreliable.