Place Representations in the Human Visual System

描述（由申请人提供）：我们是在太空中移动的生物，这一事实对我们的存在来说是最基本的。几乎所有对我们的生存至关重要的行为--寻找食物、寻找配偶和躲避捕食者--都需要在外部世界中导航。半个世纪的研究表明，人类和动物使用世界大尺度空间结构的认知“地图”来促进这种能力。用于形成这些地图的大部分信息最初是从视觉中获取的。但这提出了一个难题：我们如何将最初从特定视图和特定实例获取的视觉空间信息转换为可用于导航规划的环境空间的视点不变表示？这里提出的研究将使用功能性磁共振成像（fMRI）来解决这个问题。在前人工作的基础上，我们假设人脑支持至少三个不同层次的空间表征：（1）它表征物体和表面相对于身体各部分如眼睛和手的位置（body-space）;（二）它表示身体躯干与固定在一组固定表面上的坐标框架之间的关系，该坐标框架定义了局部场景（场景空间）;（3）它表示观察者在更大环境中的位置和方向，包括相对于当前“在地平线上”的位置（世界空间）。拟议研究的第一部分将研究海马旁和压后皮质中的场景空间表征，特别强调揭示这些表征从经验中学习并随时间变化的机制。拟议研究的第二部分将检查参与代表身体空间的神经机制，并将在功能上区分这些机制，从那些参与代表场景空间。拟议研究的第三部分将研究参与表征世界空间的神经机制。虽然这项研究并没有检查盲人的空间处理，但所获得的结果将有助于我们区分与视觉密不可分的过程和相对非模态的过程。因此，这方面的知识可能是至关重要的盲人康复策略的发展。

DESCRIPTION (provided by applicant): There are few circumstances more fundamental to our existence in the fact that we are creatures that move through space. Almost all of the behaviors are essential to our survival - locating food, finding a mate, and avoiding predators - require navigation through the external world. A half-century of research suggests that humans and animals use cognitive "maps" of the large-scale spatial structure of the world to facilitate this ability. Much of the information used to form these maps is initially acquired from vision. But this presents a puzzle: how do we transform visuospatial information initially acquired from specific views and specific instances into a viewpoint-invariant representation of environmental space that can be used for navigational planning? The research proposed here will use functional magnetic resonance imaging (fMRI) to address this question. On the basis of previous work, we hypothesize that the human brain supports at least three distinct hierarchical levels of spatial representation: (1) it represents the locations of objects and surfaces relative to various body parts such as the eye and hand (body-space); (2) it represents the relationship between the trunk of the body and a coordinate frame anchored on the set of immovable surfaces that defines the local scene (scene-space); (3) it represents the the location and orientation of the observer within the larger environment, including relative to locations that are currently "over the horizon" (world-space). The first part of the proposed research will examine scene-space representations in parahippocampal and retrosplenial cortices with particular emphasis on uncovering the mechanisms by which these representations are learned from experience and change over time. The second part of the proposed research will examine the neural mechanisms involved in representing body-space and will functionally distinguish these mechanisms from those involved in representing scene-space. The third part of the proposed research will examine the neural mechanisms involved in representing world-space. Although this research does not examine spatial processing in nonsighted individuals, the results obtained will help us to distinguish between processes that are inextricably tied to vision and those that are relatively amodal. As such, this knowledge could be critical for development of rehabilitation strategies in the blind.