| Background:Postural control has been defined as the control of the body's position in space for the purposes of stability and orientation.Multisensory integration is the base of postural control,which means that central nervous system can process and integrate redundant information from different sensory ehannels such as visual,vestibular and somatosensory information and form a coordinated internal representation.An amount of literature has showed that light touch with an extermal surface can improve upright standing performance.However,it is unclear that why tactile information can improve balance and how it can be integrated via central nervous system.Objective:According to different touching objects,it was divided into the intermal self touch and external light touch.Also,according to different touching types,it was divided into active light touch and passive light touch.Under different visual and different proprioceptive conditions,the effects of internal and external light touch,active and passive light touch on posture control were investigated,and also the meehanism of tactile-feedback information and the sensory strategy under different standing conditions were studied.Method:(1)To investigate the effect of different light contact objects on postural control,the experimental design of 2(eye open,eye closed)× 2(standing on the firm surface or foam surface)×3(no touch,light touch,self touch)was adopted.13 male subjects participated in this study,with recording surface electromyography(sEMG)signals of left and right Tibialis Anterior and Medial Gastrocnemius and Central of pressure(COP)data.(2)To investigate the effect of different light contact types on postural control,the experimental design of 2(eye open,eye closed)×2(standing on the firm surface or foam surface)X 3(no touch,light touch,passive touch)was adopted.13 male subjects participated in this study,with recording sEMG signals of left and right Tibialis Anterior and Medial Gastrocnemius and COP data.Results:(1)COP data showed that when standing on the firm surface,postural sway reduced through light touching an external stable surface only when participants were eye closed;however,when standing on the foam surface,postural sway reduced through light touching an external surface both when participants were eye open or closed.Self touch did not significantly affect postural sway.sEMG data showed that when standing on the form surface with eye closed,the relative muscle activity of right TA reduced in light touch conditions.(2)COP data showed that when standing on the firm surface,compared to no touch conditions and passive touch conditions,only light touch conditions significantly reduced postural sway;however,when standing on the foam surface,both light touch conditions and passive touch conditions significantly reduced postural sway,the effect of light touch on uprigt stability was better than that of passive touch.sEMG data showed that both light touch and passive touch conditions did not significantly affect the relative muscle activity of both left and right TA and MG.Conclusion:(1)The present findings suggest that the tactile feedback information can compensate for the disturbance of visual and proprioceptive information so as to keep upright standing balance.When vision and proprioception are not disturbed,light touching cannot affect static upright stance.However,when visual or proprioceptive information is disturbed,light touching with an external surface can improve the upright standing performance.Furthermore,when visual and proprioceptive information are both disturbed,the tactile information can be up-weighted,which significantly improves the static upright stance performance.(2)When light touching an external platform as a fixed object,the tactile feedback information obtained by the fingertips can significantly improve the static upright stance performance,which suggests that the physical spatial orientation established by the external object may be an important factor for maintaining balance. |
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