Kaptein Ronald G, Van Gisbergen Jan A M
Department of Biophysics, Radboud University Nijmegen, Geert Grooteplein 21, 6525 EZ Nijmegen, The Netherlands.
J Neurophysiol. 2006 Mar;95(3):1936-48. doi: 10.1152/jn.00856.2005. Epub 2005 Nov 30.
Using vestibular sensors to maintain visual stability during changes in head tilt, crucial when panoramic cues are not available, presents a computational challenge. Reliance on the otoliths requires a neural strategy for resolving their tilt/translation ambiguity, such as canal-otolith interaction or frequency segregation. The canal signal is subject to bandwidth limitations. In this study, we assessed the relative contribution of canal and otolith signals and investigated how they might be processed and combined. The experimental approach was to explore conditions with and without otolith contributions in a frequency range with various degrees of canal activation. We tested the perceptual stability of visual line orientation in six human subjects during passive sinusoidal roll tilt in the dark at frequencies from 0.05 to 0.4 Hz (30 degrees peak to peak). Because subjects were constantly monitoring spatial motion of a visual line in the frontal plane, the paradigm required moment-to-moment updating for ongoing ego motion. Their task was to judge the total spatial sway of the line when it rotated sinusoidally at various amplitudes. From the responses we determined how the line had to be rotated to be perceived as stable in space. Tests were taken both with (subject upright) and without (subject supine) gravity cues. Analysis of these data showed that the compensation for body rotation in the computation of line orientation in space, although always incomplete, depended on vestibular rotation frequency and on the availability of gravity cues. In the supine condition, the compensation for ego motion showed a steep increase with frequency, compatible with an integrated canal signal. The improvement of performance in the upright condition, afforded by graviceptive cues from the otoliths, showed low-pass characteristics. Simulations showed that a linear combination of an integrated canal signal and a gravity-based signal can account for these results.
在没有全景线索时，利用前庭传感器在头部倾斜变化期间维持视觉稳定性是一项计算挑战。依赖耳石需要一种神经策略来解决其倾斜/平移模糊性，例如半规管 - 耳石相互作用或频率分离。半规管信号受到带宽限制。在本研究中，我们评估了半规管和耳石信号的相对贡献，并研究了它们如何被处理和组合。实验方法是在具有不同程度半规管激活的频率范围内，探索有无耳石贡献的条件。我们测试了六名人类受试者在黑暗中以0.05至0.4 Hz（峰峰值30度）的频率进行被动正弦滚动倾斜时视觉线方向的感知稳定性。由于受试者不断监测额平面中视觉线的空间运动，该范式需要对正在进行的自我运动进行时刻更新。他们的任务是判断当线以各种幅度正弦旋转时的总空间摆动。从反应中我们确定了线必须如何旋转才能在空间中被感知为稳定。测试在有（受试者直立）和没有（受试者仰卧）重力线索的情况下都进行了。对这些数据的分析表明，在空间中线方向的计算中对身体旋转的补偿虽然总是不完整的，但取决于前庭旋转频率和重力线索的可用性。在仰卧条件下，对自我运动的补偿随频率急剧增加，与整合的半规管信号一致。由耳石的重力感知线索在直立条件下带来的性能改善表现出低通特性。模拟表明，整合的半规管信号和基于重力的信号的线性组合可以解释这些结果。
