Focused Ultrasound Activation of Vestibular Otolith Organs

在常规生物医学成像应用中使用的超声波携带动量并且向生物医学成像应用施加小的力。 在成像过程中。这种非线性声辐射力作用在超声波束的方向上， 其大小随入射超声压力的平方而增长。在大多数生物组织中， 但是如果在组织阻抗中存在大的不连续性， 反射产生附加力。在初步研究中，我们检查了超声声学的生理效应， 内耳的辐射力。当低强度超声聚焦于内耳耳石器官时， 产生了巨大的声辐射力，将耳石推向超声波束的方向，使毛发偏转， 束的方向，并调节传入神经元的动作电位放电率。该部队 主要是由于内淋巴和耳锥质量之间的声阻抗不匹配， 半规管或耳蜗中没有的此属性可用于选择性地激活单个 使用远程非侵入性超声换能器在规定的方向上对耳石器官进行超声检查。目前的R21应用是 旨在开发超声波作为耳石器官的受控刺激，并检查耳石器官的生理反应。 前庭器官和耳蜗。该技术有可能作为测试耳石器官功能的刺激物， 补偿神经回路，作为一个高度控制的刺激，用于调制个人耳石输入到大脑，并作为一个 用于前庭神经调节的非侵入性方法。

Ultrasound waves used in conventional biomedical imaging applications carry momentum and impart small forces to tissue during the imaging process. This nonlinear acoustic radiation force acts in the direction of the ultrasound beam and grows in magnitude with the square of the incident ultrasound pressure. In most biological tissues the momentum transfer arises from absorption of the ultrasound energy by the tissue, but if there is a large discontinuity in the tissue impedance additional force arises from reflection. In preliminary studies we examined physiological effects of ultrasound acoustic radiation force in the inner ear. When low intensity ultrasound was focused on the inner ear otolith organs, a relatively large acoustic radiation force was generated, pushing the otolith in the direction of the ultrasound beam, deflecting hair bundles in the direction of the beam, and modulating action potential discharge rate of afferent neurons. The force was generated primarily because of the acoustic impedance mismatch between endolymph and the otoconial mass, a mismatch that is not present in the semicircular canals or the cochlea. This property can be used to selectively activate individual otolith organs in prescribed directions using a remote noninvasive ultrasound transducer. The present R21 application is designed to develop ultrasound as controlled stimulus for otolith organs, and to examine physiological responses of vestibular organs and the cochlea. The technology has potential as a stimulus for testing the function of otolith organs and compensatory neural circuits, as a highly controlled stimulus for modulating individual otolith inputs to the brain, and as a noninvasive method for vestibular neuromodulation.