Dyhr Jonathan P, Higgins Charles M
Department of Neuroscience, The University of Arizona, 1040 E. 4th Street, Tucson, AZ 85721-0077, USA.
Biol Cybern. 2010 Dec;103(6):433-46. doi: 10.1007/s00422-010-0414-6. Epub 2010 Dec 16.
Insect navigational behaviors including obstacle avoidance, grazing landings, and visual odometry are dependent on the ability to estimate flight speed based only on visual cues. In honeybees, this visual estimate of speed is largely independent of both the direction of motion and the spatial frequency content of the image. Electrophysiological recordings from the motion-sensitive cells believed to underlie these behaviors have long supported spatio-temporally tuned correlation-type models of visual motion detection whose speed tuning changes as the spatial frequency of a stimulus is varied. The result is an apparent conflict between behavioral experiments and the electrophysiological and modeling data. In this article, we demonstrate that conventional correlation-type models are sufficient to reproduce some of the speed-dependent behaviors observed in honeybees when square wave gratings are used, contrary to the theoretical predictions. However, these models fail to match the behavioral observations for sinusoidal stimuli. Instead, we show that non-directional motion detectors, which underlie the correlation-based computation of directional motion, can be used to mimic these same behaviors even when narrowband gratings are used. The existence of such non-directional motion detectors is supported both anatomically and electrophysiologically, and they have been hypothesized to be critical in the Dipteran elementary motion detector (EMD) circuit.
昆虫的导航行为，包括避障、掠地着陆和视觉里程计，都依赖于仅根据视觉线索估计飞行速度的能力。在蜜蜂中，这种对速度的视觉估计在很大程度上独立于运动方向和图像的空间频率内容。长期以来，来自被认为是这些行为基础的运动敏感细胞的电生理记录一直支持视觉运动检测的时空调谐相关型模型，其速度调谐会随着刺激的空间频率变化而改变。结果是行为实验与电生理和建模数据之间存在明显冲突。在本文中，我们证明，与理论预测相反，当使用方波光栅时，传统的相关型模型足以重现蜜蜂中观察到的一些与速度相关的行为。然而，这些模型无法与正弦刺激的行为观察结果相匹配。相反，我们表明，作为基于相关性的方向运动计算基础的非定向运动探测器，即使在使用窄带光栅时也可用于模拟这些相同的行为。这种非定向运动探测器的存在在解剖学和电生理学上都得到了支持，并且它们被认为在双翅目基本运动探测器（EMD）电路中至关重要。
