凝视时眼睛微小运动的功能

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Nature：凝视时眼睛微小运动的功能

  生物谷报道：凝视性眼睛运动指的是眼睛不自觉的微小运动，或称“视网膜抖动”，是在我们盯住某个东西看时发生的。这种运动的功能自其在上个世纪50年代首次被发现以来一直是一个有争议的问题。Rucci等人通过将心理物理实验与对进入眼睛、以抵消眼睛运动的视觉效应的视觉信号所做的统计分析结合起来，发现如果没有这些运动，我们对细微信息的感知就会降低。这表明，凝视性眼睛运动是大脑用来从视觉信息中提取细节内容的一个策略的构成部分。

英文原文：

Nature 447, 852-855 (14 June 2007) | doi:10.1038/nature05866; Received 5 March 2007; Accepted 18 April 2007


Miniature eye movements enhance fine spatial detail
Michele Rucci1, Ramon Iovin1, Martina Poletti1 & Fabrizio Santini1

Department of Cognitive and Neural Systems, Boston University, Boston, Massachusetts 02215, USA
Correspondence to: Michele Rucci1 Correspondence and requests for materials should be addressed to M.R. (Email: rucci@cns.bu.edu).


Abstract

Our eyes are constantly in motion. Even during visual fixation, small eye movements continually jitter the location of gaze1, 2, 3, 4. It is known that visual percepts tend to fade when retinal image motion is eliminated in the laboratory5, 6, 7, 8, 9. However, it has long been debated whether, during natural viewing, fixational eye movements have functions in addition to preventing the visual scene from fading10, 11, 12, 13, 14, 15, 16, 17. In this study, we analysed the influence in humans of fixational eye movements on the discrimination of gratings masked by noise that has a power spectrum similar to that of natural images. Using a new method of retinal image stabilization18, we selectively eliminated the motion of the retinal image that normally occurs during the intersaccadic intervals of visual fixation. Here we show that fixational eye movements improve discrimination of high spatial frequency stimuli, but not of low spatial frequency stimuli. This improvement originates from the temporal modulations introduced by fixational eye movements in the visual input to the retina, which emphasize the high spatial frequency harmonics of the stimulus. In a natural visual world dominated by low spatial frequencies, fixational eye movements appear to constitute an effective sampling strategy by which the visual system enhances the processing of spatial detail.