Spering Miriam, Gegenfurtner Karl R
Department of Psychology, Justus-Liebig University Giessen, Otto-Behaghel-Str. 10F, D-35394 Giessen, Germany.
J Neurophysiol. 2007 Sep;98(3):1355-63. doi: 10.1152/jn.00476.2007. Epub 2007 Jul 18.
The analysis of visual motion serves many different functions ranging from object motion perception to the control of self-motion. The perception of visual motion and the oculomotor tracking of a moving object are known to be closely related and are assumed to be controlled by shared brain areas. We compared perceived velocity and the velocity of smooth pursuit eye movements in human observers in a paradigm that required the segmentation of target object motion from context motion. In each trial, a pursuit target and a visual context were independently perturbed simultaneously to briefly increase or decrease in speed. Observers had to accurately track the target and estimate target speed during the perturbation interval. Here we show that the same motion signals are processed in fundamentally different ways for perception and steady-state smooth pursuit eye movements. For the computation of perceived velocity, motion of the context was subtracted from target motion (motion contrast), whereas pursuit velocity was determined by the motion average (motion assimilation). We conclude that the human motion system uses these computations to optimally accomplish different functions: image segmentation for object motion perception and velocity estimation for the control of smooth pursuit eye movements.
视觉运动分析具有多种不同功能，从物体运动感知到自我运动控制。已知视觉运动感知与对移动物体的动眼跟踪密切相关，并假定由共享的脑区控制。我们在一种需要从背景运动中分割出目标物体运动的范式中，比较了人类观察者感知到的速度和平滑跟踪眼动的速度。在每次试验中，一个跟踪目标和一个视觉背景会同时独立地受到扰动，以短暂提高或降低速度。观察者必须在扰动间隔期间准确跟踪目标并估计目标速度。在此我们表明，对于感知和稳态平滑跟踪眼动，相同的运动信号以根本不同的方式进行处理。为了计算感知速度，背景运动从目标运动中被减去（运动对比），而跟踪速度则由运动平均值决定（运动同化）。我们得出结论，人类运动系统利用这些计算来最佳地完成不同功能：用于物体运动感知的图像分割以及用于平滑跟踪眼动控制的速度估计。
