THE LOCUSTS USE OF MOTION PARALLAX TO MEASURE DISTANCE
THE LOCUSTS USE OF MOTION PARALLAX TO MEASURE DISTANCE
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DOI：
10.1007/bf00192653
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发表时间：
1990-01-01
影响因子：
2.1
通讯作者：
SOBEL, EC
中科院分区：
文献类型：
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作者：
SOBEL, EC
蝗虫在扑向目标之前会进行一种视觉行为，称为凝视。凝视包括头部的侧向平移运动。Wallace（1959）首先提出，执行该行为是为了通过运动视差获得深度信息。本研究更定量地分析了凝视在蝗虫（Schistocerca americana）距离估计中的作用，试图了解所涉及的神经机制。跳跃速度与目标距离呈单调关系，可作为蝗虫判断目标距离的一个指标。通过向蝗虫展示一个在它们凝视时横向移动的目标（人工视差），可以模拟任何距离的目标的运动视差。人工视差引起的跳跃速度与相应的真实的距离引起的跳跃速度相同，表明蝗虫使用运动视差作为距离的线索。通过在同一方向上移动目标，但比蝗虫的头部更远，可以模拟目标的运动视差指定动物后面的位置。蝗虫在这种矛盾的刺激下向前跳跃，跳跃速度适合于位于模拟距离绝对值处的目标。这表明蝗虫对头部方向和图像运动之间的关系不敏感。在一只眼睛被遮挡的情况下测量蝗虫的跳跃速度，揭示了两只眼睛的视差信号之间的相互作用-蝗虫似乎将每只眼睛感知到的运动相加（或平均）。跳跃速度的预测更准确地通过目标距离，而不是通过图像位移或图像速度在凝视。这意味着蝗虫对目标距离的计算涉及到与其头部运动有关的信号。
Locusts perform a visual behavior known as peering before jumping to targets. Peering consists of a side to side translational movement of the head. Wallace (1959) first proposed that this behavior is performed in order to obtain depth information through motion parallax. The present study analyzes more quantitatively the role of peering in the locust''s (Schistocerca americana) estimation of distance in an attempt to understand the neural mechanisms involved. Jump velocity was found to be related monotonically to target distance and was used as a measure of the locust''s judgement of target distance. By presenting locusts with a target which moved laterally while they peered (artificial parallax), it was possible to simulate the motion parallax of a target at any distance. Jump velocities elicited by means of artificial parallax were the same as jump velocities elicited by the corresponding real distances, demonstrating that locusts use motion parallax as a cue to distance. By moving the target in the same direction but further than the locust''s head it was possible to simulate targets whose motion parallax specified a position behind the animal. Locusts jump forward to such paradoxical stimuli with the jump velocity appropriate for targets located at the absolute value of the simulated distance. This suggests that locusts are insensitive to the relation between the direction of head and image motion. Measurement of jump velocity in locusts with one eye occluded revealed an interaction between the parallax signals from the two eyes - locusts appear to sum (or average) the motion perceived in each eye. Jump velocity is predicted more accurately by target distance than by either image displacement or image velocity during peering. This implies that the locust''s computation of target distance involves signals concerning its own head motion.