Neural Representations of Location and Orientation in the Human Brain

描述（由申请人提供）： 导航是一个复杂的行为，涉及到整合有关多个空间结构的信息，如位置和朝向。到目前为止，这种行为的神经基础最常通过对大鼠进行电生理记录来研究。这些研究通过揭示神经元（例如，位置细胞），其激发模式编码这些空间结构中的一个或多个。虽然这些重要的发现推进了我们对啮齿动物空间认知神经相关性的理解，但仍不清楚人类大脑中是否发生了类似的过程。因此，本提案将使用先进的功能性磁共振成像（fMRI）技术来1）识别位置和面向方向的神经表征，2）阐明位置的地图样编码的特性。在实验1中，多体素模式分析（MVPA）和功能磁共振成像适应（fMRIa）将被用来寻找分布式表示的位置和面向方向，并测试这两个结构是独立或联合编码。接下来，我将扩展我早期的工作，它为海马体中空间的度量表示提供了第一个证据，该空间表示保留了位置之间的距离关系，这是认知地图的关键特征之一（Morgan et al.，In Press）.具体来说，当受试者观看校园地标的照片时，左前海马体中的BOLD信号与连续试验中显示的地标之间的真实距离成比例。我将在两个功能性磁共振成像实验中通过探测距离信号来进一步描述这种类似地图的编码。在实验2中，我将通过比较受试者观察从大环境（费城）绘制的地标时的距离信号和受试者观察从较小环境（宾夕法尼亚大学校园）绘制的地标时的距离信号，来测试地图是以一个尺度还是多个尺度表示空间。在实验3中，我将测试地图是否基于它们在欧几里得空间中的位置或不同地点之间的路线长度和角度来表示位置。为了区分这两种可能性，我将在虚拟环境中训练受试者，其中路线长度远大于某些地标对的欧几里得距离。这项提议旨在阐明人类成功寻路行为的神经表征。这种行为的困难可能源于各种神经损伤，包括脑血管意外和阿尔茨海默病。通过探测空间表征的神经位点，本研究可以改善对存在寻路困难的患者的评估和诊断，并可以通过建议利用完整脑区的应对策略来告知患者治疗。)

DESCRIPTION (provided by applicant): Navigation is a complex behavior that involves integrating information about multiple spatial constructs such as location and facing direction. To date, the neural underpinnings of this behavior have been most commonly studied by making electrophysiological recordings in rats. Such studies have contributed to our understanding of spatial cognition by revealing neurons (e.g., place cells) whose firing patterns code for one or more of these spatial constructs. Although these important discoveries have advanced our understanding of the neural correlates of rodent spatial cognition, it remains unclear whether similar processes occur in the human brain. Therefore, this proposal will use advanced functional magnetic resonance imaging (fMRI) techniques to 1) identify the neural representations of location and facing direction and 2) elucidate the properties of map-like coding of location. In Experiment 1, multivoxel pattern analysis (MVPA) and fMRI adaptation (fMRIa) will be used to look for distributed representations of location and facing direction and test whether these two constructs are coded independently or conjointly. Next, I will expand on my early work, which provided the first evidence for a metric representation of space in the hippocampus that preserves distance relationships between locations, one of the key features of a cognitive map (Morgan et al., In Press). Specifically, when subjects viewed photographs of landmarks from their campus, BOLD signal in the left anterior hippocampus scaled with the real-world distance between landmarks shown on successive trials. I will further characterize this map-like coding by probing the distance signal in two fMRI experiments. In Experiment 2, I will test whether the map represents space at one scale or multiple scales by comparing the distance signal when subjects view landmarks drawn from a large environment (the city of Philadelphia) to the distance signal when subjects view landmarks drawn from a smaller environment (the University of Pennsylvania campus). In Experiment 3, I will test whether the map represents locations based on their position in Euclidean space or the route length and angles between different places. To distinguish between these two possibilities, I will train subjects on a virtual environment where the route length is much longer than the Euclidean distance for some landmark pairs. This proposal aims to elucidate the neural representations that allow successful wayfinding behavior in humans. Difficulties with this behavior can arise from a variety of neurological insults including cerebrovascular accidents and Alzheimer's Disease. By probing the neural locus of spatial representations, this research can improve the assessment and diagnosis of patients that present with wayfinding difficulties and may inform patient treatments by suggesting coping strategies that utilize the intact brain areas. )