Function of fixational instability during natural viewing

描述（由申请人提供）：在注视过程中，我们通常没有意识到的小眼球运动会阻止我们保持稳定的凝视方向。众所周知，在实验室中，当视网膜运动被消除时，图像往往会褪色。然而，长期以来，人们一直在争论，在自然观看过程中，眼球的注视运动是否不仅仅是防止视觉场景褪色。在之前的试点研究补助金中进行的实验结果表明，正如我们的模型所预测的那样，注视眼运动有助于对精细空间细节的感知，并且已经推测了一个多世纪。本研究拟结合人类受试者的心理物理实验、早期视觉系统神经元的计算建模和视网膜视觉输入的统计分析，研究固定眼动在模式视觉中的作用。心理物理实验将检验在自然视觉固定的短暂眼间期，对有或没有视网膜图像运动的刺激的检测和辨别。为了克服先前视网膜稳定研究的技术限制，实验将依赖于一种新的注视随动显示系统，该系统可以严格比较正常视网膜运动和视网膜稳定两种情况。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)随机交替进行有或没有视网膜图像运动的试验，以及(c)独立于受试者自己的判断评估视网膜稳定的准确性。计算研究将检查实验对象所经历的视觉输入信号，并模拟视网膜、外侧膝状核和纹状皮层神经元的反应。对于每一次实验，模拟将复制受试者在眼球运动过程中的神经元活动。受试者的表现和神经元反应传递的刺激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不正常的眼球固定运动。除了促进我们对视觉感知的基本理解外，对固定不稳定的功能影响的理解可能会导致与此类疾病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.