Cognitive Neuroscience Centre, UMR CNRS 5229, University of Lyon I, 69500 Bron, France.
J Neurosci. 2011 Jul 6;31(27):10039-49. doi: 10.1523/JNEUROSCI.0492-11.2011.
Saccades are imprecise, due to sensory and motor noise. To avoid an accumulation of errors during sequences of saccades, a prediction derived from the efference copy can be combined with the reafferent visual feedback to adjust the following eye movement. By varying the information quantity of the visual feedback, we investigated how the reliability of the visual information affects the postsaccadic update in humans. Two elements of the visual scene were manipulated, the saccade target or the background, presented either together or in isolation. We determined the weight of the postsaccadic visual information by measuring the effect of intrasaccadic visual shifts on the following saccade. We confirmed that the weight of visual information evolves with information quantity as predicted for a statistically optimal system. In particular, we found that the visual background alone can guide the postsaccadic update, and that information from target and background are optimally combined. Moreover, these visual weights are adjusted dynamically and on a trial-to-trial basis to the level of visual noise determined by target eccentricity and reaction time. In contrast, we uncovered a dissociation between the visual signals used to update the next planned saccade (main saccade) and those used to generate an involuntary corrective saccade. The latter was exclusively based on visual information about the target, and discarded all information about the background: a suboptimal use of visual evidence.
扫视是不精确的，这是由于感觉和运动噪声造成的。为了避免在扫视序列中累积误差，可以将来自传出副本的预测与再传入的视觉反馈相结合，以调整后续的眼球运动。通过改变视觉反馈的信息量，我们研究了视觉信息的可靠性如何影响人类的扫视后更新。我们操纵了视觉场景的两个元素，即扫视目标或背景，它们要么一起呈现，要么单独呈现。我们通过测量内扫视视觉转移对视后扫视的影响来确定扫视后视觉信息的权重。我们证实，视觉信息的权重随着信息量的变化而变化，这与统计最优系统的预测相符。特别是，我们发现仅背景视觉就可以引导扫视后的更新，并且目标和背景的信息可以得到最佳组合。此外，这些视觉权重会根据目标偏心和反应时间确定的视觉噪声水平进行动态调整和逐次调整。相比之下，我们发现用于更新下一个计划扫视（主扫视）的视觉信号与用于生成无意识校正扫视的信号之间存在分离。后者仅基于关于目标的视觉信息，并丢弃了关于背景的所有信息：这是对视觉证据的次优利用。
