How We Keep Our Balance
Falls can be a problem for older people, so the news that scientists have zeroed in on exactly how we maintain our balance bodes well for finding ways to prevent slips, trips, and tumbles. A team from McGill University, physiologists Kathleen Cullen and Maurice Chacron, have demonstrated that the brain reacts to stimuli with a preference for unexpected motions rather than in order of appearance, so to speak. This how the vestibular system in the labyrinth of the inner ear allows us to keep our balance when, for example, we accidentally step off a curb while not paying attention or try to walk on a narrow surface.
"Although it is well established that the neural code representing the world changes at each stage of a sensory pathway, the transformations that mediate these changes are not well understood," the authors wrote. "Here we show that self-motion (i.e. vestibular) sensory information encoded by VIIIth nerve afferents is integrated nonlinearly by post-synaptic central vestibular neurons . . .These findings challenge the traditional notion that the vestibular system uses a linear rate code to transmit information and have important consequences for understanding how the representation of sensory information changes across sensory pathways."