Adaptive postural control for a repeated perturbation

A postural perturbation paradigm was developed to study the adaptation of neural control strategy for a repeated perturbation to the upright standing. The perturbation was an impulse-like pulling force at the pelvis level. A warning signal was given to the subject before the perturbation. The performance improved quickly after a few trials. All subjects could restore the standing posture using ankle strategy for the same level of perturbation that induced stepping in the beginning. The adaptation was a slight swing in the opposite direction of the perturbation. The magnitude of EMG activities in response to the perturbation reduced after adaptation. It is suggested that a feedforward control adjustment in terms of changes in the initial condition was introduced to reduce the impact of the perturbation to the body balance. This feedforward control strategy was immediately abolished after the change of perturbation. The performance deteriorated as a consequence