Central and peripheral mechanisms contributing to human balance control

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We have all seen the effect that fear, anxiety and confidence can have on the ability to control balance. Just think of someone trying to walk across a balance beam. If the beam is on the ground, most people usually have no difficulty to walk across it; however, if it is raised high in the air, people are likely to lose their balance and fall. Interestingly, the only thing that has changed in those two conditions is the threat or consequence of a fall. The emotional response to the threat of falling is one factor that we believe may contribute to balance problems and falls in older adults and people with balance disorders. Our research has shown that increased threat and arousal in otherwise healthy individuals can directly influence the way they control balance. However, the specific way in which threat influences the brain's ability to control balance is currently unknown. Therefore, the short term goal of the research program is to understand how threat influences dynamic balance responses, and may influence the way the brain receives and processes sensory information relevant to controlling balance. This research is part of my long term goal to understand how the brain, sensory systems and muscles contribute to healthy and pathological balance. We will manipulate threat by having subjects perform balance tasks while standing on a physical, or virtual (using 3D virtual reality), platform that can be raised to different heights. A series of studies will be performed to assess how threat influences our ability to respond to unexpected balance disturbances and discover how threat influences sensory systems responsible for detecting movement of the body and head. Balance performance will be assessed from ground-reaction forces, motion analysis and muscular activity recorded during quiet standing and balance perturbations. Knowledge developed from the proposed research program will be used to identify the specific neural mechanisms that are involved in threat-related changes in human balance control and will improve our understanding of how links between emotion and balance may contribute to balance deficits and falls.