|
Description:
|
The whole body acts as a gaze stabilization system : head -torso activity and lower body movement are coordinated to provide a stable retinal image during locomotion . Body loading is a fundamental parameter that modulates motor output during locomotion , and is especially important for controlling the generation of stepping patterns , dynamic balance , and termination of locomotion . Increased body weight support (BWS ) during locomotion results in an immediate reorganization of locomotor control , such as a reduction in stance and double support duration and decreased hip , ankle , and knee angles during the gait cycle . Until now , no studies have investigated how gaze control systems respond to adaptive modification in the body load sensing system . The goal of this research is to determine the role of body load -regulating mechanisms in gaze control during locomotion . The general hypothesis behind the proposed research is that body load -regulating mechanisms contribute to gaze stabilization , and adaptive changes in these load -regulating mechanisms will require reorganization in the full -body gaze control system so that visual acuity can be maintained during locomotion .
To support the hypothesis of this study , head -torso coordination , lower limb movement patterns , and gait cycle timing were evaluated before and after a 30 -minute adaptation session during which subjects walked on a treadmill at 5 .4 km /hr with 40 % body weight support (BWS ) . Before and after the adaptation period , head -torso and lower limb 3D kinematic data were obtained during locomotion using a video -based motion analysis system , and gait cycle timing parameters were collected by foot switches positioned under the heel and toe of the subjects shoes . The predominant changes observed in the subjects were a result of adaptive modification in the body load -regulating mechanisms and included increased head movements , increased knee and ankle flexion , and increased stance , stride , and double support time , with no change in dynamic visual acuity . Therefore , it is evident that just 30 minutes of 40 % BWS during locomotion was enough sensory conflict to induce adaptive modifications in the sensory systems that contribute to locomotor control , and these modifications represent an overall reorganization of vestibular -somatosensory interactions in the full -body integrated gaze stabilization system . |