The human vestibular system provides sensory input to the brain regarding movement of the head, including both lateral and angular accelerations. The semi-circular canals sense angular movements in all three orthogonal axes, while the otoliths sense movements due to lateral motion including gravity. Proper function of the vestibular system is critical for maintaining balance while standing or walking, as well as for stabilizing vision. Vestibular disorders can range from minor to debilitating, affecting a significant portion of the population, especially the elderly. Many currently available research tools, diagnostic equipment, and treatments for vestibular disorders require exciting the peripheral vestibular organs by physically moving the subject, which often poses significant challenges. Prosthesis devices capable of improving postural stability in the balance-impaired, particularly for those elderly prone to falls, are also needed. It seems likely that the proposed electromagnetic means of stimulating the vestibular system will fill the need for enhanced techniques in vestibular research within multiple areas of interest to the NIDCD. This Small Business Innovation Research Phase I project proposes investigation of the effects of time-varying magnetic fields on the human vestibular system and the potential to develop non-invasive research, diagnostic, treatment, or prosthetic devices based on the observed effects. The proposing firm has hypothesized that the applied magnetic field exerts Lorenz force on the transduction currents flowing through the hair bundle into the hair cell. This force is expected to cause the hair bundle to move and thereby start a chain reaction that leads to altered output of the sensory hair cell, creating a spurious input to the brain. Multiple studies have shown that strong static magnetic fields can cause nausea, dizziness, or vertigo, but the physical basis for the effect has not been determined. Previous work led by the proposing firm has dealt with much weaker time- varying magnetic fields. Effects of such fields on vestibular bundles have been modeled, and preliminary experiments with a live mouse subjected to applied magnetic fields has shown a possible effect on the afferent firing rate of a vestibular hair cell. The purpose of this project will be to verify the origin of the magnetic field effect on the vestibular system, characterize the effect, and determine the feasibility of using it for development of equipment for diagnosing or treating vestibular disorders, and ultimately for the development of a vestibular prosthesis device. Relevance Disorders of the human vestibular system, or sense of balance, can range from minor to debilitating, affecting a significant portion of the population, especially the elderly. Research tools, diagnostic equipment, and treatments for vestibular disorders are needed that do not require physically moving the subject, which often poses significant challenges. Prosthesis devices capable of improving postural stability in the balance-impaired, particularly for those elderly prone to falls, are also needed. The proposed electromagnetic means of stimulating the vestibular system via time-varying magnetic fields is a truly innovative concept that will potentially provide a unique capabilities and research opportunities in this critical area. ? ? ?
