Zanker J M, Srinivasan M V, Egelhaaf M
Centre for Visual Sciences, RSBS, Australian National University, GPO Box 475, Canberra, ACT 2601, Australia.
Biol Cybern. 1999 Feb;80(2):109-16. doi: 10.1007/s004220050509.
A prominent model of visual motion detection is the so-called correlation or Reichardt detector. Whereas this model can account for many properties of motion vision, from humans to insects (review, Borst and Egelhaaf 1989), it has been commonly assumed that this scheme of motion detection is not well suited to the measurement of image velocity. This is because the commonly used version of the model, which incorporates two unidirectional motion detectors with opposite preferred directions, produces a response which varies not only with the velocity of the image, but also with its spatial structure and contrast. On the other hand, information on image velocity can be crucial in various contexts, and a number of recent behavioural experiments suggest that insects do extract velocity for navigational purposes (review, Srinivasan et al. 1996). Here we show that other versions of the correlation model, which consists of a single unidirectional motion detector or incorporates two oppositely directed detectors with unequal sensitivities, produce responses which vary with image speed and display tuning curves that are substantially independent of the spatial structure of the image. This surprising feature suggests simple strategies of reducing ambiguities in the estimation of speed by using components of neural hardware that are already known to exist in the visual system.
一种著名的视觉运动检测模型是所谓的相关或赖夏特检测器。尽管该模型可以解释从人类到昆虫的许多运动视觉特性（综述见Borst和Egelhaaf，1989年），但人们普遍认为这种运动检测方案不太适合测量图像速度。这是因为该模型常用的版本包含两个具有相反偏好方向的单向运动检测器，其产生的响应不仅随图像速度变化，还随其空间结构和对比度变化。另一方面，图像速度信息在各种情况下都可能至关重要，最近的一些行为实验表明昆虫确实会为了导航目的提取速度信息（综述见Srinivasan等人，1996年）。在此我们表明，相关模型的其他版本，即由单个单向运动检测器组成或包含两个灵敏度不等的相反方向检测器的版本，产生的响应随图像速度变化，并且显示出基本独立于图像空间结构的调谐曲线。这一惊人特性表明，通过使用视觉系统中已知存在的神经硬件组件，可以采用简单策略减少速度估计中的模糊性。
