Department of Otolaryngology, University of Rochester, Rochester, NY 14642, USA.
Exp Brain Res. 2012 Jun;219(3):369-79. doi: 10.1007/s00221-012-3099-3. Epub 2012 May 5.
Detection of asymmetries has been a mainstay of using vestibular reflexes to assess semicircular canal function. However, there has been relatively little work on how vestibular stimuli are perceived. Suprathreshold vestibular perception was measured in 13 normal healthy controls by having them compare the relative sizes of two yaw (vertical-axis rotation) or sway (right-left translation) stimuli. Both stimuli were 1.5 s in duration with a staircase used to adjust the relative size of the stimuli to find a pair of stimuli perceived as equal. Motion stimuli were delivered in darkness using a hexapod motion platform, and visual stimuli simulating motion were presented on a screen in the absence of platform motion. Both same direction (SD) and opposite direction (OD) stimuli were delivered in separate runs. After a two-interval stimulus, subjects reported which movement they perceived as larger. Cumulative distribution functions were fit to the responses so that the relative magnitudes of the two stimuli perceived as equal could be determined. For OD trial blocks, a directional asymmetry index was calculated to compare the relative size of perceived rightward and leftward motion. For all trial blocks, a temporal asymmetry index (TAI) was used to compare the relative size of the first and second intervals. Motion OD stimuli were perceived as equal in all subjects in yaw and all but one in sway. For visual OD stimuli, two subjects had slightly asymmetric responses for both sway and yaw. The TAI demonstrated asymmetry in 54% in yaw, in which the second interval was perceived to be larger in all but one subject who had an asymmetry. For sway, only two subjects had a significant asymmetry. Visual stimuli produced a similar rate of asymmetry. The direction and magnitude of these asymmetries were not significantly correlated with those seen for motion stimuli. Asymmetries were found in a fraction with the TAI in SD stimuli for motion in yaw (42%) and sway (33%), as well as for vision in yaw (60%) and sway (43%). The precision at discriminating SD motion stimuli decreased significantly with age, but there was no difference in OD motion or visual stimuli.
检测不对称性一直是使用前庭反射来评估半规管功能的主要方法。然而，对于前庭刺激是如何被感知的，相关研究相对较少。通过让 13 名正常健康对照者比较两个偏航（垂直轴旋转）或摇摆（左右平移）刺激的相对大小，测量了阈上前庭感知。两种刺激的持续时间均为 1.5 秒，使用阶梯法调整刺激的相对大小，以找到一对被感知为相等的刺激。在黑暗中使用六足运动平台提供运动刺激，在没有平台运动的情况下，在屏幕上呈现模拟运动的视觉刺激。在单独的运行中，分别提供相同方向（SD）和相反方向（OD）的刺激。在两次间隔刺激后，受试者报告他们感知到哪个运动更大。将累积分布函数拟合到响应中，以确定被感知为相等的两个刺激的相对大小。对于 OD 试验块，计算方向不对称指数以比较感知到的向右和向左运动的相对大小。对于所有试验块，使用时间不对称指数（TAI）来比较第一和第二间隔的相对大小。在所有受试者的偏航和所有受试者的摇摆中，OD 运动刺激被感知为相等。对于视觉 OD 刺激，有两名受试者在摇摆和偏航中都有轻微的不对称反应。TAI 在偏航中表现出不对称性，在所有受试者中，除了一名受试者的不对称性外，第二间隔被感知为更大。对于摇摆，只有两名受试者有显著的不对称性。视觉刺激产生了类似的不对称率。这些不对称性的方向和大小与运动刺激的不对称性没有显著相关性。在偏航中的运动（42%）和摇摆（33%）以及偏航中的视觉（60%）和摇摆（43%）的 SD 刺激中，TAI 存在一定程度的不对称性。用于区分 SD 运动刺激的精度随着年龄的增长显著下降，但 OD 运动或视觉刺激没有差异。
