Representation of spatial coordinate systems within posterior parietal cortex and hippocampus

为了准确地伸手拿到物体或从一个房间走到另一个房间，我们的大脑需要能够定位我们周围的物体，并检测我们路径上的障碍。我们有一种惊人的能力，能够直接将眼睛准确地对准一杯茶等物体，并顺畅地将手直接对准杯子，这是我们都认为理所当然的事情。然而，这种能力需要巨大的计算复杂性，而我们的大脑已经进化到可以轻松处理。我们计划通过使用一种名为功能磁共振成像或功能磁共振成像的相对较新的技术来确定执行这些计算的大脑部分。这是一种非侵入性技术，需要人躺在核磁共振扫描仪中，在扫描仪拍摄大脑图像的同时执行简单的眼动任务。有了这项技术，我们能够确定在每项任务的执行过程中，大脑的哪些区域最活跃，从而让我们深入了解大脑是如何工作的。大脑中一个叫做顶叶的区域被认为与物体的定位有关，比如伸手去喝杯茶。我们将使用功能磁共振成像来研究这个区域，以确定空间地图在顶叶内是如何表现的。大脑的这个区域与另一个区域进行交流，海马体被认为参与导航，比如在房子里走来走去或在城市里开车。当受试者在计算机屏幕上模拟的迷宫中执行简单的导航任务时，功能核磁共振将被用于研究他们的海马体。这将揭示海马体在导航中的作用，以及顶叶和海马体之间的关系。我们希望，通过这项研究对海马体的更多了解将使我们能够设计出一种健壮的方法，用功能磁共振成像来成像海马体功能。我们期望这些技术将有助于诊断颞叶癫痫患者的海马区异常。

To accurately reach for an object or walk from one room to another, our brains need to be able to locate objects around us and detect obstacles in our path. Our amazing ability to make an accurate eye movement directly towards an object such as a cup of tea and move our hand smoothly and directly to the cup is something we all take for granted. However, this ability requires enormous computational complexity which our brains have evolved to handle with ease. We plan to determine the parts of the brain that perform these computations by using a relatively new technique called functional magnetic resonance imaging or fMRI. This is a non-invasive technique that requires a person to lie in an MRI scanner and perform simple eye movement tasks while the scanner takes images of the brain. With this technology we are able to determine which regions of the brain are most active during the performance of each task, thereby giving us an insight into how the brain works. An area of the brain called the parietal lobe is thought to be involved in the localization of objects, such as reaching for a cup of tea. We will study this area using fMRI to determine how a map of space is represented within the parietal lobe. This region of the brain communicates with another region, the hippocampus which is thought to be involved in navigation, such as walking about the house or driving in the city. Functional MRI will be used to study the hippocampus of our subjects while they perform simple navigational tasks through a maze which is simulated on a computer screen. This will reveal the role hippocampus plays in navigation and the relationship between the parietal lobe and hippocampus. We hope that the greater understanding of hippocampus that will arise from this study will enable us to devise a robust method for imaging hippocampal function with fMRI. We expect that these techniques will aid in the diagnosis of hippocampal abnormalities in patients with temporal lobe epilepsy.