Pavan Andrea, Casco Clara, Mather George, Bellacosa Rosilari M, Cuturi Luigi F, Campana Gianluca
SISSA, Cognitive Neuroscience Sector, Via Bonomea 265, 34136 Trieste, Italy.
Vision Res. 2011 Sep 15;51(18):2077-84. doi: 10.1016/j.visres.2011.08.001. Epub 2011 Aug 9.
A series of experiments investigated the extent to which the spatial orientation of a signal line affects discrimination of its trajectory from the random trajectories of background noise lines. The orientation of the signal line was either parallel (iso-) or orthogonal (ortho-) to its motion direction and it was identical in all respects to the noise (orientation, length and speed) except for its motion direction, rendering the signal line indistinguishable from the noise on a frame-to-frame basis. We found that discrimination of ortho-trajectories was generally better than iso-trajectories. Discrimination of ortho-trajectories was largely immune to the effects of spatial jitter in the trajectory, and to variations in step size and line-length. Discrimination of iso-trajectories was reliable provided that step-size was not too short and did not exceed line length, and that the trajectory was straight. The new result that trajectory discrimination in moving line elements is modulated by line orientation suggests that ortho- and iso-trajectory discrimination rely upon two distinct mechanisms: iso-motion discrimination involves a 'motion-streak' process that combines motion information with information about orientation parallel to the motion trajectory, while ortho-motion discrimination involves extended trajectory facilitation in a network of receptive fields with orthogonal orientation tuning.
一系列实验研究了信号线的空间方向在多大程度上影响其轨迹与背景噪声线随机轨迹的区分。信号线的方向与其运动方向平行（等向）或正交（正交），除运动方向外，在所有方面（方向、长度和速度）都与噪声相同，使得信号线在逐帧基础上与噪声无法区分。我们发现，正交轨迹的区分通常优于等向轨迹。正交轨迹的区分在很大程度上不受轨迹空间抖动以及步长和线长变化的影响。只要步长不太短且不超过线长，并且轨迹是直的，等向轨迹的区分就是可靠的。移动线元中轨迹区分受线方向调制这一新结果表明，正交和等向轨迹区分依赖于两种不同的机制：等向运动区分涉及一个“运动条纹”过程，该过程将运动信息与平行于运动轨迹的方向信息相结合，而正交运动区分涉及在具有正交方向调谐的感受野网络中扩展轨迹促进作用。
