Andreescu Corina E, De Ruiter Martijn M, De Zeeuw Chris I, De Jeu Marcel T G
Department of Neuroscience, Erasmus University Medical Center Rotterdam, Dr. Rotterdam, The Netherlands.
J Neurophysiol. 2005 Nov;94(5):3487-96. doi: 10.1152/jn.00147.2005. Epub 2005 Aug 3.
According to the multisensory integration theory vestibular, optokinetic and proprioceptive inputs act in concert to maintain a stable retinal image of the visual world. Yet, it remains elusive to what extent the otolith organs contribute to this process and whether a specific loss of otolith input is compensated for. Here we investigated the compensatory eye movements in tilted mice, which lack otoconia because of a mutation in otopetrin 1. Tilted mice showed very small displacements of the eyes in the orbit during static roll paradigms, suggesting the absence of functional otolith organs. Independent of head position with respect to gravity, the gain and phase lead of angular vestibuloocular reflex of tilted mice were decreased and increased, respectively (frequencies 0.2 to 1 Hz and peak accelerations 8 to 197 degrees /s2, respectively). Furthermore, lack of otolith input increases the dependency of the vestibular system on stimulus frequency. In contrast, the gain of optokinetic reflex in tilted mice was significantly higher in the low-frequency range than in control mice, regardless of the position of the mice in space or the plane of the eye movements. To explain these results, a simple model was used in which a multisensory integration unit was embedded. With this model, we were able to simulate all the behaviors observed. Thus our data and the model support the presence of the multisensory integration system and revealed a compensatory enhanced optokinetic reflex in tilted mice, indicating an adaptive synergism in the processing of otolith and visually driven signals.
根据多感官整合理论，前庭、视动和本体感觉输入协同作用，以维持视觉世界稳定的视网膜图像。然而，耳石器官在这一过程中的贡献程度以及耳石输入的特定缺失是否得到补偿，仍不清楚。在这里，我们研究了倾斜小鼠的代偿性眼动，这些小鼠由于耳钙黏蛋白1的突变而缺乏耳石。在静态侧倾范式中，倾斜小鼠的眼睛在眼眶内的位移非常小，这表明耳石器官功能缺失。与头部相对于重力的位置无关，倾斜小鼠的角前庭眼反射增益和相位超前分别降低和增加（频率分别为0.2至1Hz，峰值加速度为8至197度/s²）。此外，耳石输入的缺失增加了前庭系统对刺激频率的依赖性。相比之下，无论小鼠在空间中的位置或眼动平面如何，倾斜小鼠在低频范围内的视动反射增益均显著高于对照小鼠。为了解释这些结果，我们使用了一个嵌入多感官整合单元的简单模型。利用这个模型，我们能够模拟观察到的所有行为。因此，我们的数据和模型支持多感官整合系统的存在，并揭示了倾斜小鼠代偿性增强的视动反射，表明在耳石和视觉驱动信号处理中存在适应性协同作用。
