Funding: The National Institute of Aging
Impaired balance control may arise from neurological problems such as loss of inner ear (vestibular) function. Deficits in one sensory system can also affect how intact sensory systems contribute to postural control. For example, patients without vestibular function commonly relate no difficulty walking on hard support surfaces, but report discomfort walking on “spongy” surfaces (e.g., grass) that disrupt the processing of sensory information at the feet. The daily life of such individuals is severely hampered by such balance problems. 
In collaboration with Dr. Fay Horak and Dr. Robert Peterka at OHSU, Rob Creath and I studied individuals with vestibular loss to understand how they use sensory information compared to individuals with intact sensory systems. Pictured (larger view) is a vestibular loss subject standing on a surface that can rotate around the ankle joint in a rhythmic fashion. This rotating surface makes the task of standing much more difficult and we study how body position is controlled as the surface rotates at different rates. At the same time, different conditions vary the available sensory information to see how balance control is affected.
One of the important findings was that the postural control of vestibular loss individuals improves enormously with light touch contact of a stationary surface. With light touch, their postural control is equivalent to healthy individuals with an intact vestibular system.
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Publications
Jeka JJ, Kiemel T, Creath R, Horak FB, Peterka R (2004) Controlling human upright stance: Velocity information is more accurate than position or acceleration. Journal of Neurophysiology, 92, 2368-2379.
Creath R, Kiemel T, Horak FB, Jeka JJ (2002). Limited control strategies with the loss of
vestibular function. Experimental Brain Research, 145(3), 323-333.
Horak FB, Buchanan J, Creath R, Jeka JJ (2002). Vestibulospinal control of posture. Adv. Exp Med Biol., 508, 139-145.
Lackner, J.R., DiZio, P., Jeka, J.J., Horak, F.H., Krebs, D. & Rabin, E. (1999). Precision contact of the fingertip reduces postural sway of individuals with bilateral vestibular loss. Experimental Brain Research, 126, 459-466.
Jeka, J.J. (1998). Touching surfaces for control not support. In D. Rosenbaum & C. Collyer (Eds.), Timing of Behavior: Neural, Computational, and Psychological Perspectives. Cambridge: MIT press.
Keywords: Posture control, aging, Fall risk, Vestibular Deficits,