Function of fixational instability during natural viewing

描述(申请人提供)：在视觉注视过程中，我们通常没有意识到的微小的眼球运动阻碍了稳定的凝视方向的保持。众所周知，当在实验室中消除视网膜运动时，图像往往会褪色。然而，长期以来，人们一直在争论，在自然观看的过程中，凝视的眼球运动是否不仅仅是防止视觉场景褪色。在前一次领航研究拨款期间进行的实验结果表明，正如我们的模型所预测的和一个多世纪以来所推测的那样，凝视的眼球运动有助于感知精细的空间细节。这项建议描述了一项研究计划，将心理物理实验与人类受试者相结合，对早期视觉系统中的神经元进行计算建模，并对视觉输入视网膜进行统计分析，以研究凝视眼球运动在模式视觉中的贡献。心理物理学实验将检验在自然视觉注视的短暂眼跳间歇期，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识别。为了克服以前关于视网膜稳定的研究的技术限制，实验将依赖于一种新的视线相关显示系统，该系统可以在正常视网膜运动和视网膜稳定这两种情况下进行严格的比较。该系统使我们能够(A)选择性地稳定眼跳后的刺激，这是一种保持眼睛正常注视运动的条件，(B)随机交替进行有无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。计算研究将检查受试者在实验中经历的视觉输入信号，并模拟视网膜、外侧膝状体和纹状皮质神经元的反应。对于每个实验试验，一个模拟将复制受试者进行的眼球运动序列中的神经元活动。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异常的凝视眼球运动。除了促进我们对视觉感知的基本理解外，对注视不稳定的功能暗示的理解可能会导致治疗通常与这种情况相关的视觉损伤。

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.