The Function Of Different Visual Information Components In Anticipatory Postural Adjustments

Background: Upright standing is a special posture which only in human beings.Because of the reduce of standing area and the raise of centre of gravity,upright standing is an unstable posture.Internal and external perturbations can increase the probability of fall.When human beings face to perturbations,anticipatory postural adjustments(APAs)and compensatory postural adjustments(CPAs)are two frequently-used strategies.APAs are before perturbations,and they can also reduce the strength of CPAs.Vision is an important channel for human beings to obtain external information,so it plays an important role in postural control.Objective and Method: This study divide visual information into three levels,and design three experiments to inform the function of different visual information components in APAs.The classic ball hitting test is adopt in this study.Experiment 1 divide visual information into three conditions(open eyes,OE \open eyes with a baffle,OEB\close eyes,CE)to explore the function of anticipatory information and environment information in postural control.Experiment 2 divide visual information into three conditions(open eyes,OE\signal lamp,SL\open eyes with a baffle,OEB)to explore the different function of optical flow information and signal information in APAs.Experiment 3 give two groups of subjects separately 30 trials OE and SL training,to explore the acquisitus mode of APAs.Results: Experiment 1: The pre-action time of OE was significant early than OEB and CE,but OEB and CE had no significant difference.The IEMG of OE had significant difference with OEB and CE,but OEB and CE had no significant difference.Experiment 2: The pre-action time of SL is significant early than OEB but significant latter than OE in biceps brachii\lumbar spine\lateral personal.The APAs' IEMG of SL is significant greater than OEB but significant smaller than OE in biceps brachii.The CPAs' IEMG is significant greater than OE but significant smaller than OEB in lateral personeal.Experiment 3: The interaction effect of pre-action time in two types of training is significant in biceps brachii.The interaction effect of APAs' IEMG in two types of training is significant in lumbar spine.Conclusion:(1)Anticipatory information can effect postural adjustment before perturbation,and then influence the CPAs after perturbation;but environment information can only effect the CPAs after perturbation.(2)Signal information can cause APAs,but this adjustments' modes are different with the ones which anticipatory information caused(such as the delay of activition time and the reduce of contraction strength).(3)After short time training,the improve of APAs which caused by signal information are more than the ones caused by anticipatory information.So the daily experience is an important way to acquire APAs.(4)Because of the function of environment information and ankle joint,the measurement of them cannot be exclude.