Place Representations in the Human Visual System

描述(申请人提供)：对于我们的存在来说，很少有比这更基本的情况了，因为我们是在太空中移动的生物。几乎所有的行为对我们的生存都是必不可少的--寻找食物、寻找配偶、躲避捕食者--需要通过外部世界导航。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”来促进这一能力。用于形成这些地图的大部分信息最初是从视觉获得的。但这带来了一个难题：我们如何将最初从特定视图和特定实例获得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，我们假设人脑至少支持三个不同的层次空间表征：(1)它代表物体和表面相对于身体不同部分的位置，如眼睛和手(身体-空间)；(2)它代表身体躯干和固定在定义局部场景(场景-空间)的一组表面上的坐标系之间的关系；(3)它代表观察者在更大环境中的位置和方向，包括相对于目前在地平线上的位置(世界空间)。这项拟议研究的第一部分将检查海马体旁和脾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和随着时间的变化而变化的机制。这项拟议研究的第二部分将研究涉及表征身体空间的神经机制，并在功能上将这些机制与那些涉及表征场景空间的机制区分开来。这项拟议研究的第三部分将研究代表世界空间的神经机制。虽然这项研究没有考察失明个体的空间加工，但所获得的结果将帮助我们区分与视觉有着千丝万缕联系的加工和相对不稳定的加工。因此，这些知识可能对盲人康复策略的制定至关重要。

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.