Function of fixational instability during natural viewing

描述（由申请人提供）：在视觉注视期间，我们通常没有意识到的小眼球运动阻止了稳定的注视方向的维持。众所周知，当在实验室中消除视网膜运动时，图像趋于褪色。然而，长期以来，人们一直在争论，在自然观看过程中，注视性眼球运动是否不仅仅是防止视觉场景褪色。在先前的试点研究资助期间进行的实验结果表明，注视眼球运动有助于感知精细的空间细节，正如我们的模型所预测的那样，并推测了超过世纪。该建议描述了一个研究计划，该计划结合了人类受试者的心理物理学实验，早期视觉系统神经元的计算建模，以及视网膜视觉输入的统计分析，以研究注视眼动在模式视觉中的贡献。心理物理学实验将检查在自然视觉注视的短暂扫视间期间，在有和没有视网膜图像运动的情况下，对所呈现的刺激的检测和辨别。为了克服以前视网膜稳定研究的技术局限性，实验将依赖于一种新的凝视视情况显示系统，该系统能够在正常视网膜运动和视网膜稳定两种情况之间进行严格的比较。该系统使我们能够（a）在扫视后选择性地稳定刺激，这是一种保持眼睛正常注视运动的条件，（B）在有和没有视网膜图像运动的情况下随机交替试验，以及（c）独立于受试者自己的判断来评估视网膜稳定的准确性。计算研究将检查实验中受试者所经历的视觉输入信号，并模拟视网膜、外侧膝状体核和纹状体皮质中神经元的反应。对于每个实验性试验，模拟将复制受试者进行的眼球运动序列期间的神经元活动。受试者的表现和关于神经元反应传递的刺激的信息将在逐个试验的基础上进行比较。许多视觉障碍表现为异常的注视性眼球运动。除了推进我们对视觉感知的基本理解外，对注视不稳定的功能影响的理解可能会导致通常与此类条件相关的视觉障碍的治疗。

DESCRIPTION (provided by applicant): During visual fixation, small eye movements of which we are usually not aware, prevent the maintenance of a steady direction of gaze. It is known that images tend to fade when retinal motion is eliminated in the laboratory. However, it has long been debated whether, during natural viewing, fixational eye movements do more than prevent the visual scene from fading. The results of experiments conducted during a previous Grant for Pilot Research indicate that fixational eye movements contribute to the perception of fine spatial detail, as predicted by our models and as speculated for more than a century. This proposal describes a program of research, which combines psychophysical experiments with human subjects, computational modeling of neurons in the early visual system, and statistical analysis of the visual input the retina to study the contributions of fixational eye movements in pattern vision. Psychophysical experiments will examine the detection and discrimination of stimuli presented, with and without retinal image motion, during the brief intersaccadic periods of natural visual fixation. To overcome the technical limitations of previous studies on retinal stabilization, experiments will rely on a new system of gaze-contingent display, which enables rigorous comparison between the two conditions of normal retinal motion and retinal stabilization. This system enables us to (a) selectively stabilize the stimulus after a saccade, a condition that preserves the normal fixational motion of the eye, (b) randomly alternate trials with and without retinal image motion, and (c) assess the accuracy of retinal stabilization independently of the subject's own judgment. Computational studies will examine the visual input signals experienced by subjects in the experiments, and simulate the responses of neurons in the retina, the lateral geniculate nucleus, and the striate cortex. For every experimental trial, a simulation will replicate neuronal activity during the sequence of eye movements performed by the subject. Subject performance and information about the stimulus transmitted by neuronal responses will be compared on a trial-by-trial basis. A number of visual disorders manifest abnormal fixational eye movements. In addition to advancing our basic understanding of visual perception, a comprehension of the functional implications of fixational instability may lead to treatment of the visual impairments commonly associated with such conditions.