Sustained and Transient Vestibular Systems: A Physiological Basis for Interpreting Vestibular Function.
Sustained and Transient Vestibular Systems: A Physiological Basis for Interpreting Vestibular Function.
复制标题
DOI：
10.3389/fneur.2017.00117
复制
发表时间：
2017
影响因子：
3.4
通讯作者：
de Waele C
中科院分区：
文献类型：
--
作者：
Curthoys IS;MacDougall HG;Vidal PP;de Waele C
有规律静息放电的耳石传入神经响应重力或低频线性加速度，我们称这些为静态或持续耳石系统。然而，在耳石感觉器官中，存在着跨斑的解剖分化和相应的生理分化。一组特殊的受体叫做纹状体，主要由I型受体组成，它们的毛束被微弱地系在耳石膜上。在I型纹状体受体上形成萼状突触的传入神经元具有不规则的静息放电，对高频（例如500 Hz）骨传导振动和空气传导声音具有低阈值。高频率的声音和振动可能会导致流体位移，从而使非常快速的I型感受器的微弱系住的毛发束偏转。不规则的前庭传入信号与耳蜗传入信号相似，表现为相锁，刺激频率高达千赫兹。我们把这些不规则的传入称为瞬时系统信号动态耳石刺激。500赫兹的振动优先激活耳石不规则传入神经，因为常规传入神经在临床试验中使用的强度下不会被激活，而不规则传入神经的阈值较低。我们展示了这种持续和短暂的区别如何适用于前庭核。这两个系统对振动和声音、耳毒性抗生素、电刺激和自然线性加速度有不同的反应，这种不同的灵敏度允许探测这两个系统。500赫兹的振动选择性地激活不规则的耳石传入，导致动物和人类的刺激锁定眼球运动。这些眼球运动的预备肌电位是在耳石功能-眼前庭诱发肌电位的新临床试验中测量的。我们认为，500赫兹的振动可以确定瞬态系统对前庭控制反应的贡献，如前庭-眼反应、前庭-脊髓反应和前庭-交感反应。在临床上，通过使用优先攻击I型受体的鼓室内庆大霉素，针对一种或另一种瞬时或持续系统的特殊治疗的前景正在实现。我们认为通过这种持续-短暂的区别来观察前庭反应是有价值的。
Otolithic afferents with regular resting discharge respond to gravity or low-frequency linear accelerations, and we term these the static or sustained otolithic system. However, in the otolithic sense organs, there is anatomical differentiation across the maculae and corresponding physiological differentiation. A specialized band of receptors called the striola consists of mainly type I receptors whose hair bundles are weakly tethered to the overlying otolithic membrane. The afferent neurons, which form calyx synapses on type I striolar receptors, have irregular resting discharge and have low thresholds to high frequency (e.g., 500 Hz) bone-conducted vibration and air-conducted sound. High-frequency sound and vibration likely causes fluid displacement which deflects the weakly tethered hair bundles of the very fast type I receptors. Irregular vestibular afferents show phase locking, similar to cochlear afferents, up to stimulus frequencies of kilohertz. We term these irregular afferents the transient system signaling dynamic otolithic stimulation. A 500-Hz vibration preferentially activates the otolith irregular afferents, since regular afferents are not activated at intensities used in clinical testing, whereas irregular afferents have low thresholds. We show how this sustained and transient distinction applies at the vestibular nuclei. The two systems have differential responses to vibration and sound, to ototoxic antibiotics, to galvanic stimulation, and to natural linear acceleration, and such differential sensitivity allows probing of the two systems. A 500-Hz vibration that selectively activates irregular otolithic afferents results in stimulus-locked eye movements in animals and humans. The preparatory myogenic potentials for these eye movements are measured in the new clinical test of otolith function—ocular vestibular-evoked myogenic potentials. We suggest 500-Hz vibration may identify the contribution of the transient system to vestibular controlled responses, such as vestibulo-ocular, vestibulo-spinal, and vestibulo-sympathetic responses. The prospect of particular treatments targeting one or the other of the transient or sustained systems is now being realized in the clinic by the use of intratympanic gentamicin which preferentially attacks type I receptors. We suggest that it is valuable to view vestibular responses by this sustained-transient distinction.