Abstract
Motivation: To properly control postural balance, good coordination between visual, vestibular and muscle control system must be maintained. It has been documented that deteriorated visual abilities such as visual acuity, contrast sensitivity and depth perception are related to the deficits in postural control. However, little attention has been paid to the relation between motion detection sensitivity and postural control, which is an important gap in literature because motion signal is crucial in maintaining balance. Methods: Twenty older (67-78) and twenty young adults (19-24) underwent series of tasks measuring visual and postural control abilities. Visual tasks include visual acuity, contrast sensitivity, depth perception and motion sensitivity tasks. Motion sensitivity was determined by measuring duration thresholds in two sizes and two contrasts conditions. Postural control tasks include maintaining upright stance in different combination of visual aid and floor conditions, and shifting the center of mass to certain location without stepping out from initial position. Results: We replicated existing findings that contrast sensitivity and visual acuity are related to the ability of shifting center of mass accurately (P< 0.01, r=0.523 and P< 0.01, r=0.526 respectively). More importantly, we found that motion sensitivities to different size of stimulus are related to different abilities of balance control. Sensitivity to large motion stimulus is negatively correlated with the ability of maintaining upright stance (P< 0.001, r=-0.540), and sensitivity to small motion stimulus is positively correlated with the ability of shifting center of mass accurately (P< 0.001, r=0.670). Discussion: The improvement of perceptual sensitivity to a large-high contrast motion in older adults indicates that deteriorated ability of suppressing irrelevant motion signals. Our current finding that the size of motion stimulus affects the correlation between motion perception and balancing differently suggests that suppression of irrelevant peripheral motion signal might have critical role in controlling balance.
Meeting abstract presented at VSS 2017