Neural Basis of Depth Perception

描述(申请人提供)：我们几乎毫不费力地与我们的三维(3D)视觉环境中的对象交互，然而在每只眼睛的视网膜上形成的图像只是3D空间的二维投影，不包含关于深度的明确信息。因此，视觉系统的一个基本任务是从每只眼睛的视网膜上形成的图像重建3D场景结构。关于深度的定量信息主要由两种视觉线索携带：双目视差和运动视差。这项研究的总体目标是了解这些深度线索是在哪里以及如何由视觉皮质中的神经元处理的，以调节我们对3D世界的感知。这项建议描述了解决关于深度知觉的神经基础的两个基本问题的实验。在目标1中，我们将使用可逆失活技术来探索背侧和腹侧视觉加工流对立体深度知觉的作用。通过灭活MT和V4区，我们将检验这样的假设：背侧流主要处理绝对视差来计算物体在3D空间中的位置，而腹侧流主要处理相对视差来计算3D形状和精细深度结构。在目标2中，我们将对视觉系统如何根据运动视差计算深度进行第一次神经生理学研究。由观察者的移动引起的运动视差对于深度的符号(相对于凝视点的近距离和远距离)基本上是模糊的。因此，运动视差通常必须与视网膜外信号相结合才能计算深度标志。我们将测试MT区的神经元是否将视网膜图像运动与视网膜外信号结合起来，从运动视差计算深度，并探索参与这一过程的视网膜外信号的来源。这项研究解决了神经活动如何产生视觉感知的基本问题，并探索了视网膜外信号如何与视觉处理相互作用，以在大脑中进行有趣的计算。因此，这项工作解决了国家眼科研究所的国家眼睛和视觉研究计划的计划目标之一。这项工作与健康相关的最终价值将源于对认知功能如何用神经活动来解释的更深层次的理解。了解正常观察者的大脑活动和心理功能之间的联系，将有助于更深入地了解各种精神障碍的原因。

DESCRIPTION (provided by applicant): We interact almost effortlessly with objects in our three-dimensional (3D) visual environment, yet the image formed on the retina of each eye is simply a two-dimensional projection of 3D space that contains no explicit information about depth. Thus, a fundamental task of the visual system is to reconstruct 3D scene structure from the images formed on the retina of each eye. Quantitative information about depth is mainly carried by two visual cues: binocular disparity and motion parallax. The overall goal of this research is to understand where and how these depth cues are processed by neurons in the visual cortex to mediate our perception of a 3D world. This proposal describes experiments that address two fundamental issues regarding the neural basis of depth perception. In Aim #1, we will use a reversible inactivation technique to explore the roles that the dorsal and ventral visual processing streams make to stereoscopic depth perception. By inactivating areas MT and V4, we will test the hypothesis that the dorsal stream mainly processes absolute disparities to compute the location of objects in 3D space, whereas the ventral stream mainly processes relative disparities to compute 3D shape and fine depth structure. In Aim #2, we will carry out the first neurophysiological studies of how the visual system computes depth from motion parallax. Motion parallax resulting from movement of the observer is fundamentally ambiguous regarding the sign of depth (near versus far relative to the point of fixation). As a result, motion parallax generally must be combined with extraretinal signals to compute depth sign. We will test whether neurons in area MT combine retinal image motion with extraretinal signals to compute depth from motion parallax, and we will explore the origins of the extraretinal signals involved in this process. This research addresses the fundamental issue of how neural activity gives rise to visual perception, and also explores how extraretinal signals interact with visual processing to carry out interesting computations in the brain. Thus, this work addresses one of the Program Goals of the National Eye Institute's National Plan for Eye and Vision Research. The ultimate health-related value of this work will follow from a deeper understanding of how cognitive functions can be explained in terms of neural activity. Understanding the links between brain activity and mental function in normal observers will provide a deeper appreciation of the causes of various mental disorders.