Grunfeld E A, Okada T, Jáuregui-Renaud K, Bronstein A M
MRC Human Movement and Balance Unit, Institute of Neurology, National Hospital for Neurology and Neurosurgery, London, United Kingdom.
J Vestib Res. 2000;10(4-5):193-200.
A technique was applied to assess vestibular sensation without reference to external spatial, position cues. The stimuli were stopping responses to velocity-steps of 90 deg/s in the dark. Subjects indicated their perceived angular velocity by turning a flywheel connected to a tachogenerator. Two separate experiments were conducted. In one, subjects were rotated in yaw about an earth-vertical axis before and after prolonged rotational or visual (optokinetic) stimuli. In the second experiment, subjects were rotated in roll supine, with either the head ('roll centred') or the feet ('roll eccentric') on the axis of rotation. The two aims of the paper were to (i) examine the effect of repetitive vestibular and optokinetic stimulation on the time constant of decay of vestibular sensation in yaw; (ii) to compare vestibular sensation responses to rotation in roll both with and without the addition of a Z-axis centrifugal force. The pre-habituation sensation response in yaw decayed exponentially with a median time constant of 12.8 s. The duration of the sensation responses were significantly reduced following both prolonged vestibular and optokinetic stimulation. The reduction in vestibular responses following prolonged visual and vestibular stimuli, 1) is likely to occur in velocity storage mechanisms mediating ocular and perceptual responses, 2) may represent a mechanism for reducing the disorientating consequences of visual-vestibular conflict and 3) supports the use of optokinetic stimuli as a treatment for vestibular patients. The time constant of the sensation responses in roll was shorter and not significantly influenced by head position: 5.7 s in the head-centred position compared to 4.7 s in the eccentric head position. Therefore, perceptual as well as ocular responses to rotation in roll are determined primarily by cupula dynamics and not influenced by velocity storage.
应用了一种技术来评估前庭感觉，而无需参考外部空间位置线索。刺激是在黑暗中对90度/秒速度阶跃的停止反应。受试者通过转动与测速发电机相连的飞轮来表明他们感知到的角速度。进行了两个独立的实验。在一个实验中，受试者在长时间的旋转或视觉（视动）刺激前后绕地球垂直轴进行偏航旋转。在第二个实验中，受试者仰卧进行横滚旋转，头部（“横滚居中”）或脚部（“横滚偏心”）位于旋转轴上。本文的两个目的是：（i）研究重复性前庭和视动刺激对偏航前庭感觉衰减时间常数的影响；（ii）比较在有和没有Z轴离心力的情况下，横滚旋转时的前庭感觉反应。偏航中习惯化前的感觉反应呈指数衰减，中位时间常数为12.8秒。长时间的前庭和视动刺激后，感觉反应的持续时间均显著缩短。长时间视觉和前庭刺激后前庭反应的降低：1）可能发生在介导眼动和感知反应的速度存储机制中；2）可能代表一种减少视觉-前庭冲突定向障碍后果的机制；3）支持使用视动刺激作为前庭患者的一种治疗方法。横滚感觉反应的时间常数较短，且不受头部位置的显著影响：头部居中位置为5.7秒，而偏心头部位置为4.7秒。因此，横滚旋转时的感知以及眼动反应主要由壶腹动力学决定，而不受速度存储的影响。
