Neural Representations of Location and Orientation in the Human Brain

描述(由申请人提供)： 导航是一种复杂的行为，涉及集成有关位置和朝向等多个空间结构的信息。到目前为止，这种行为的神经基础大多是通过在大鼠身上进行电生理记录来研究的。这类研究通过揭示神经元(例如，位置细胞)的放电模式编码了一个或多个空间结构，有助于我们理解空间认知。尽管这些重要的发现促进了我们对啮齿动物空间认知的神经关联的理解，但目前还不清楚类似的过程是否发生在人脑中。因此，这项建议将使用先进的功能磁共振成像(FMRI)技术来1)识别位置和面向方向的神经表征，2)阐明位置的地图状编码的特性。在实验1中，将使用多体素模式分析(MVPA)和功能磁共振自适应(FMRIa)来寻找位置和面对方向的分布式表征，并测试这两个结构是独立编码还是联合编码。接下来，我将扩展我的早期工作，该工作为海马体中空间的度量表示提供了第一个证据，该度量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等人，在Press中)。具体地说，当受试者观看校园地标的照片时，左前海马区的大胆信号随着连续试验中显示的地标之间的真实距离而增大。我将通过在两个fMRI实验中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看来自大环境(费城)的地标时的距离信号和观看来自较小环境(宾夕法尼亚大学校园)的地标时的距离信号，来测试地图是以一种尺度还是多种尺度来表示空间。在实验3中，我将测试地图是否根据位置在欧几里德空间中的位置或不同地点之间的路线长度和角度来表示地点。为了区分这两种可能性，我将在虚拟环境中训练受试者，在这种环境中，路线长度比一些地标对的欧几里德距离要长得多。这项提议旨在阐明在人类中允许成功的寻路行为的神经表征。这种行为的困难可能源于各种神经侮辱，包括脑血管意外和阿尔茨海默病。通过探索空间表征的神经轨迹，这项研究可以改善对出现认路困难的患者的评估和诊断，并可能通过建议利用完整大脑区域的应对策略来指导患者的治疗。) 公共卫生相关性： 这项提议使用神经成像方法来理解人脑如何表示有关导航的位置和面向方向的信息。通过探索这些空间表征，这项研究可以改善对存在寻路困难的患者(例如，中风患者和阿尔茨海默病患者)的评估和诊断，并可能通过建议利用完整大脑区域的应对策略来指导患者治疗。

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. ) PUBLIC HEALTH RELEVANCE: This proposal uses neuroimaging methods to understand how the human brain represents information about location and facing direction to navigate. By probing these spatial representations, this research can improve the assessment and diagnosis of patients that present with wayfinding difficulties (e.g., stroke victims and patients with Alzheimer's Disease) and may inform patient treatments by suggesting coping strategies that utilize the intact brain areas.