Contrast dependence of smooth pursuit eye movements following a saccade to superimposed targets.
Contrast dependence of smooth pursuit eye movements following a saccade to superimposed targets.
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DOI：
10.1371/journal.pone.0037888
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发表时间：
2012
期刊：
影响因子：
3.7
通讯作者：
Reynolds JH
中科院分区：
文献类型：
--
作者：
Fallah M;Reynolds JH
背流区域提供由眼动系统使用的运动信息以生成追踪眼球运动。这些区域中的神经元在低水平的亮度对比下饱和。因此，我们假设，在早期阶段的追求，眼速将表现出一个眼动增益函数，饱和在低亮度对比度。为了验证这一点，我们记录了两只猕猴的眼球运动，猕猴被训练扫视到一个光圈，光圈中有一个向左或向右移动的圆点图案。在扫视结束后不久，眼睛跟随运动的方向，在饱和之前随着对比度的增加而增加。添加第二种模式的点，在相反的方向上移动，并叠加在第一个，导致对比度依赖性的眼动增益函数的一个相移。这种偏移的幅度随着第二图案的点的对比度而增加。当两种模式的对比度相等时，运动被取消。接下来，我们随着时间的推移改变对比度。对比度差异在扫视开始前消失，使短潜伏期的扫视后眼动产生偏差。在扫视终止期间或之后发生的对比度的变化并没有影响眼球运动约150毫秒。早期的研究发现，眼球运动可以解释为一个矢量平均计算时，两个目标是相等的对比度。我们认为，这种平均计算可能反映了分裂归一化的特殊情况下，产生饱和的对比度响应函数，向右移动与相反的运动，平均运动时，目标等同于对比度。
Dorsal stream areas provide motion information used by the oculomotor system to generate pursuit eye movements. Neurons in these areas saturate at low levels of luminance contrast. We therefore hypothesized that during the early phase of pursuit, eye velocity would exhibit an oculomotor gain function that saturates at low luminance contrast. To test this, we recorded eye movements in two macaques trained to saccade to an aperture in which a pattern of dots moved left or right. Shortly after the end of the saccade, the eyes followed the direction of motion with an oculomotor gain that increased with contrast before saturating. The addition of a second pattern of dots, moving in the opposite direction and superimposed on the first, resulted in a rightward shift of the contrast-dependent oculomotor gain function. The magnitude of this shift increased with the contrast of the second pattern of dots. Motion was nulled when the two patterns were equal in contrast. Next, we varied contrast over time. Contrast differences that disappeared before saccade onset biased post-saccadic eye movements at short latency. Changes in contrast occurring during or after saccade termination did not influence eye movements for approximately 150 ms. Earlier studies found that eye movements can be explained by a vector average computation when both targets are equal in contrast. We suggest that this averaging computation may reflect a special case of divisive normalization, yielding saturating contrast response functions that shift to the right with opposed motion, averaging motions when targets are equated in contrast.
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