MODULATION OF VESTIBULAR EVOKED REFLEXES IN POSTURAL MUSCLES DURING SELF-MOTION EXPERIENCES IN A VIRTUAL SIMULATION
43.504, Monday, May 13, 8:30 am - 12:30 pm, Vista Ballroom
Fabricio Saucedo1, Rebecca Reed-Jones1; 1Department of Kinesiology, The University of Texas at El Paso
Hidden formatting deleted. Delete this text! mso-layout-grid-align:none;text-autospace:none">Maintaining posture requires the integration of several systems: musculoskeletal, somatosensory, visual, and vestibular. The visual and vestibular systems contribute the greatest amount of information regarding the environment and the position and orientation of the body with respect to the environment. Therefore, how visual and vestibular systems work together is critical to understanding how humans maintain upright stance. The purpose of this study was to determine if dynamic visual stimuli alter central vestibular function and/or modify motor commands for postural control. Ten young adults performed 20 standing trials (60-second duration) in four sensory conditions: Control (No stimulus), Visual Only, Galvanic Vestibular Stimulation (GVS) + Visual, and GVS Only. Participants stood quietly on a force platform with their heads turned at a 90-degree angle with gaze directed to a screen at their side. Measures of center of pressure (COP) variability assessed postural control during the four sensory conditions. The analysis of COP variability revealed a significant difference between the Visual Only and GVS Only conditions (p < 0.05) with COP variability being lowest in the Visual Only condition and greatest in the GVS Only condition. In the combined vestibular and visual condition, COP variability fell between the two single sensory conditions. These results indicate an interaction between the two sensory systems, where visual stimuli reduces vestibular influence on postural control. In addition to COP measures, EMG of the soleus, tibialis anterior, and gastrocnemius muscles were recorded bilaterally. Hidden formatting deleted. Delete this text! 15.0pt;font-family:"Times New Roman";mso-fareast-font-family:Cambria; mso-bidi-font-family:Calibri">Further discussion of these EMG measures and the modulation of GVS evoked muscle reflexes with altered visual input will provide further information regarding modulation of central vestibular function and postural control.