OCULAR RESPONSES TO TRANSLATION AND THEIR DEPENDENCE ON VIEWING DISTANCE .1. MOTION OF THE OBSERVER
OCULAR RESPONSES TO TRANSLATION AND THEIR DEPENDENCE ON VIEWING DISTANCE .1. MOTION OF THE OBSERVER
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DOI：
10.1152/jn.1991.66.3.851
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发表时间：
1991-09-01
影响因子：
2.5
通讯作者：
MILES, FA
中科院分区：
文献类型：
--
作者：
SCHWARZ, U;MILES, FA
1. 利用电磁搜索线圈技术，记录了5只猕猴（Macaca mulatta）沿耳间轴加速引起的水平眼动。动物坐在雪橇上，在黑暗中沿着线性轨道短暂移动（钟形加速度曲线：峰值400毫米/秒；持续时间200毫秒）。在加速之前，动物们盯着距离16到150厘米的5个目标灯中的一个。在注视过程中，双眼水平位置用于检查散度，同时用红外验光仪监测调节。雪橇运动引起的眼球运动通常是平滑的和代偿性的，例如，向右的雪橇运动引起向左的眼球运动。我们将这些反应归因于通过耳石器官感知滑车运动的平移前庭反射（TVOR）。然而，在3只动物中，这些反应之前有微弱的抗代偿运动（持续时间< 40 ms，幅度<最大代偿反应的10%）。几何学表明，在短暂的雪橇运动中，保持视线对准特定位置（“完全”补偿）所需的眼球运动与观看距离成反比。基于计算的眼速度曲线的反应测量，如在特定时间（“时间片”）达到的速度或估计的协方差函数的峰值，都表明补偿反应是先前观看距离的反比的线性函数。尽管详细的频谱分析显示高频分量（bb0 ~ 10hz）比低频分量的尺度反应更弱，但相关分析表明，前视距离对尺度反应有影响。通过计算增益（记录的反应/完全补偿所需的反应）来评估补偿性眼动的充分性。无论使用何种反应测量方法，不同动物之间的增益差异很大，在某些特定的动物中，增益从一个方向到另一个方向，但总的趋势是随着观看距离的增加而增加。例如，基于雪橇运动开始250毫秒内达到的峰值眼速，16厘米处的平均增益为0.74（范围，0.48-1.01），而150厘米处的平均增益为1.25（范围，0.67-1.73）。使用楔形棱镜分离聚光和调节表明，眼球对雪橇运动的反应对聚光（离底棱镜与最远目标）或调节（离底棱镜与最近目标）的选择性增加都很敏感。然而，这种影响的程度在不同的动物之间表现出相当大的差异，在某些特定的动物中，从一个方向到另一个方向。此外，无论是单独的收敛或调节，还是两个线索的线性组合，都不能解释所有的数据。我们得出的结论是：1)平移加速度可以引发强大的补偿性眼动，显示出所需的线性依赖于接近度，尽管在这里使用的贫困条件下（黑暗）存在相当大的主体间差异；2)根据观察距离调节眼球补偿性运动时使用了收敛和调节线索，但它们往往不是唯一的线索。
1. The horizontal eye movements induced by acceleration along the interaural axis were recorded from five monkeys (Macaca mulatta) by the use of the electromagnetic search-coil technique. Animals sat on a sled that was moved briefly in darkness along a linear track (bell-shaped acceleration profile: peak, 400 mm/s2; duration, 200 ms). Immediately before acceleration, animals fixated one of five target lights located at distances ranging from 16 to 150 cm. During fixation, the horizontal positions of both eyes were used to check vergence, while accommodation was monitored with an infrared optometer.2. Sled motion induced eye movements that were generally smooth and compensatory, e.g., rightward sled motion elicited leftward eye movement. We attribute these responses to a translational vestibuloocular reflex (TVOR) that senses the sled motion through the otolith organs. However, in three animals, these responses were preceded by weak anticompensatory movements (duration, < 40 ms; amplitude, < 10% of the maximum compensatory response).3. Geometry indicates that, during brief sled motion, the eye movements required to keep gaze aligned on a particular location ("full" compensation) are inversely proportional to the viewing distance. Response measures based on the computed eye velocity profiles, such as the velocity achieved at specific times ("time slices") or the peak values of the estimated covariance functions, all indicated that compensatory responses were a linear function of the inverse of the prior viewing distance. Cross-correlation analyses indicated that the effect of the prior viewing distance was to scale responses, although detailed spectral analyses revealed that high-frequency components (> 10 Hz) tended to scale less vigorously than lower ones.4. The adequacy of the compensatory eye movements was assessed by calculating the gain (response recorded/response required for full compensation). Regardless of the response measure used, gains varied considerably from one animal to another and, in some particular animals, from one direction to another but showed a general tendency to increase with viewing distance. For example, on the basis of the peak eye velocity achieved within 250 ms of the onset of sled motion, mean gain at 16 cm was 0.74 (range, 0.48-1.01), whereas at 150 cm it was 1.25 (range, 0.67-1.73).5. Using wedge prisms to dissociate vergence and accommodation indicated that ocular responses to sled motion were sensitive to selective increases in either vergence (base-out prism with the most distant target) or accommodation (base-in prism with the nearest target). However, the magnitude of the effects showed considerable variability from one animal to another and, in some particular animals, from one direction to another. Further, neither vergence nor accommodation alone nor a linear combination of the two cues could account for all of the data.6. We conclude that 1) translational accelerations can elicit robust compensatory eye movements that show the required linear dependence on proximity, although with considerable intersubject variability in the impoverished conditions used here (darkness); 2) vergence and accommodation cues are used to modulate compensatory eye movements in accordance with viewing distance, but they are often not the only cues used.