Experimental validation of a clinical indicator of utricular function.

前庭系统负责我们的平衡感，它位于内耳，负责保持姿势，并在头部运动时帮助生物体进行适当的眼球运动。疾病或事故对前庭系统的损害对病人来说是极其虚弱的。我们研究项目的一个主要目标是开发简单的前庭系统测试，可用于临床诊断前庭系统疾病。目前大多数临床测试只测试前庭系统中对角度旋转有反应的部分（半规管）。很少有好的测试可以可靠地诊断与感觉位置（耳石）有关的问题。最近来自人类研究的证据表明，通过位于耳后皮肤表面的电极传递小电流（电刺激），会产生一种典型的眼球运动模式。我们的假设是，这种独特的眼球运动模式是耳石刺激的结果。这个项目的目的是确定这些小电流是如何产生眼球运动的，以及这些眼球运动是否实际上是由耳石调节的。为了确定这些反应背后的生理机制，我们无法在人类身上进行这些实验。因此，我们目前的计划将在豚鼠身上使用行为和生理实验来验证我们关于电刺激和耳石功能的假设。这项工作的意义在于，它将导致一种新的方法来评估人体前庭系统的重力感应部分的功能，这对有平衡问题的患者来说似乎是独特的重要。

The vestibular system is responsible for our sense of balance, it is located in the inner ear and is responsible for maintaining posture and helping an organism to make appropriate eye movements when the head moves. Damage to the vestibular system by disease or accident is extremely debilitating for a patient. A chief goal of our research program is to develop simple tests of the vestibular system that can be used in the clinic to diagnose vestibular disorders. Most present clinical tests only test the part of the vestibular system that responds to angular rotations (the semicircular canals). There are few good tests that can reliably diagnose problems concerned with sensed position (the otoliths). Recent evidence from human studies has shown that by delivering small electrical currents (galvanic stimulation) via electrodes located on the surface of the skin behind the ears, a characteristic pattern of eye movement occurs. Our hypothesis is that the distinctive pattern of eye movement produced is a result of otolith stimulation. The aim of this project is to determine exactly how these small currents produce the eye movements and if these eye movements are in fact mediated by the otoliths. To determine the physiology that underlies these types of responses we are unable to conduct these experiments in humans. Our present program will therefore use both behavioural and physiological experiments on guinea pigs to test our hypotheses about galvanic stimulation and otolith function. The significance of this work lies in that it will lead to a new way of evaluating the function of the gravity sensing part of the human vestibular system which appear to be uniquely important for patients with balance problems.