COORDINATE TRANSFORMATION IN AFTEREFFECTS AND ATTENTION

当眼睛运动导致光学图像在视网膜上移动时，视觉场景似乎不会发生变化，但是当眼睛静止时发生相同的视网膜位移时，视觉场景就会发生变化。在眼球运动过程中，视觉系统是如何实现这种“位置恒定性”的？这个项目的目标是了解坐标变换，使位置恒定性，通过生成一个身体或环境为中心的描述对象从他们的眼睛为中心的表示。而不是传统的方法来解决这个问题，测量一个短暂闪烁的点刺激的错位，我们将研究各种类型的后效/线索效应，包括视觉后效（例如。图形和运动），视觉运动后效（例如，扫视和手臂到达）和注意诱导的运动错觉（“射击”线运动效应）。关注这些效应，我们可以研究与整体空间背景相关的坐标转换过程，从而具有更高的顺序和生物学意义。典型的实验将包括一个适应（提示）阶段，和一个测试阶段，以测量负面的后效（或错觉运动的强度/方向）。然而，与传统的程序不同，在适应和测试之间将有一个重新注视阶段，其中注视点将移动，并且在测试呈现之前，将要求受试者对其进行扫视或平滑追踪眼球运动。这种操作使我们能够在坐标系或地图中隔离适应的位置，包括以眼睛为中心的位置和非以眼睛为中心的位置，即以头部、身体和环境为中心的位置。通过在不同位置呈现测试刺激，我们将获得效应的空间调谐曲线并应用互相关。分析以找出视觉系统保持以眼睛为中心的表示和/或将其转换为非以眼睛为中心的描述的程度。如果我们发现一个重要的非眼睛为中心的组成部分，如我们的试点研究所示，我们将通过在前庭椅上旋转观察者的头部和/或躯干来准确地确定哪个非眼睛为中心的系统（头部，身体或环境为中心）是相关的。我们将进一步比较主动和被动的头部/身体转动条件，以确定有助于这种转换过程的头部位置上的视网膜外信号的性质。这些结果将弥合动物生理学和人类心理物理学之间的差距，并提供深入了解坐标转换的过程。

Visual scenes do not appear to shift when an eye movement causes the optical image to move across the retina, but do when the same retinal displacement occurs while the eyes are stationary. How does the visual system achieve this "position constancy" during eye movements? The goal of this project is to understand the coordinate transformations which enable position constancy by generating a body- or environment-centered description of objects from their eye-centered representation. Instead of the traditional approach to this problem, measuring mislocalization of a briefly flashed dot stimulus, we will examine various types of aftereffect/cue effect, including visual aftereffects (eg. figural, and motion), visual-motor aftereffects (eg. saccade. and arm reaching) and an attention-induced motion illusion (the "shooting" line motion effect) by employing what we call the fixation/refixation paradigm. Focusing on such effects, we could investigate the coordinate transformation process which is relevant to the overall spatial context, and thus higher-order and biologically significant. The typical experiment will consist of an adapting (cueing) phase, and a testing phase to measure negative aftereffect (or strength/direction of the illusory motion). Unlike the conventional procedure, however, there will be a refixation phase between the adapting and the testing in which the fixation point will move, and the subject will be asked to make either a saccade or smooth pursuit eye movement to it before the test presentation. This manipulation enables us to isolate the adapted location in coordinate systems or maps, including the eye-centered and the non-eyecentered, i.e. the head-, the body-, and the environment-centered. By presenting the test stimulus at various locations, we will obtain a spatial tuning curve of the effect and apply a cross-correlation. analysis to find out the degree to which the visual system maintains the eye-centered representation, and/or transfers it into a non-eye-centered description. If we find a significant non-eye-centered component, as indicated by our pilot studies, we will determine exactly which non-eye-centered system (head-, body-, or environment-centered) is relevant by rotating the observer's head and/or torso in a vestibular chair. We will further compare active and passive head/body turn conditions to identify the nature of extraretinal signals on head position which contribute to this transformation process. The results will bridge the gap between animal physiology and human psychophysics, and provide insights into-the processes underlying coordinate transformations.