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，视觉场景似乎不会移动，但当眼睛静止时发生相同的视网膜移位时，视觉场景会发生变化。视觉系统是如何在眼球运动中实现这种“位置恒定”的？这个项目的目标是理解坐标变换，通过从以眼睛为中心的表示生成对象的以身体或环境为中心的描述来实现位置恒定。不同于传统的解决这个问题的方法，测量短暂闪光点刺激的错位化，我们将检查各种类型的后效/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。和手臂伸展)和注意力诱导的运动错觉(“射击”线条运动效应)，通过使用我们所称的注视/再注视范式。聚焦于这些影响，我们可以研究与整个空间背景相关的坐标变换过程，从而具有更高的阶数和生物学意义。典型的实验将由适应(暗示)阶段和测试阶段组成，以测量负面后效(或虚幻运动的强度/方向)。然而，与传统程序不同的是，在适应和测试之间将有一个重新注视阶段，在这个阶段中，注视点将移动，在测试呈现之前，受试者将被要求对其进行眼跳或平滑追逐眼球运动。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和非以眼睛为中心的，即以头部、身体和环境为中心。通过在不同位置呈现测试刺激，我们将获得效果的空间调谐曲线并应用互相关。分析以找出视觉系统在多大程度上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。如果我们发现了一个重要的非以眼睛为中心的部分，正如我们的初步研究所表明的那样，我们将通过在前庭椅子上旋转观察者的头部和/或躯干来准确地确定哪个非以眼睛为中心的系统(头部、身体或环境中心)是相关的。我们将进一步比较主动和被动的头部/身体旋转条件，以确定有助于这种转换过程的视网膜外信号在头部位置的性质。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，并提供对坐标转换潜在过程的洞察。

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.