High Resolution Scanning Magnetometry

描述（由申请人提供）：在第一阶段，我们建议测试基于一个简单但新颖的主源镜（PRISM）概念开发神经科学高分辨率扫描磁强计的可行性。PRISM可以有不同的设计，但在这个项目中，它将是一个充气的玻璃移液器，末端有一个小玻璃板，倾斜45度。我们声称，当我们完成该项目的第二期时，该镜子可以用于可视化体外神经元组织中无论源方向如何的电流分布，其空间分辨率高达10 5m。众所周知，在导电介质（如充满盐水的浴缸或人的头部）外部的磁场完全是由与导电边界相切的电流引起的。以人脑为例，脑磁图（MEG）只能测量脑-气边界的切向电流，而不能测量径向电流。在泡澡的神经组织中，磁场仅仅是由与泡澡表面切向而不是垂直的电流产生的。这一基本限制限制了生物磁术的使用。在第一阶段，我们将在物理模型中使用PRISM来测试PRISM是否会使浴缸中的垂直定向电流“可见”。当这面镜子被浸入神经组织上方的生理盐水中时，当一群神经元在镜子下方产生垂直或水平的细胞内电流时，它就会产生垂直于其表面的所谓次级源。根据我们的模拟研究，PRISM上的次级源的水平分量将使垂直电流对浴槽上方的磁力计“可见”。我们将使用边界元方法将结果与实际模拟研究进行比较，以充分反映实验条件。我们将进一步评估该技术的两个重要特性，这可能使我们能够在第二阶段开发高分辨率扫描磁强计。我们将测试我们的说法：(1)空间分辨率主要取决于镜子和下方活动神经元之间的距离，而不是浴缸上方磁场感应线圈与活动神经元体积之间的距离；(2)空间分辨率与检测线圈尺寸无关（在合理范围内）。这些结果将使我们能够在第二阶段开发一种新的高分辨率扫描磁强计。

DESCRIPTION (provided by applicant): In Phase I we propose to test the feasibility of developing a high-resolution scanning magnetometry for neuroscience based on a simple, but novel concept of primary source mirror (PRISM). The PRISM can be made with different designs, but in this project it will be an air-filled glass pipette with a small glass plate at the end with a tilt of 45o toward bottom. We claim that this mirror can be used to visualize the current distribution regardless of source orientations in an in vitro neuronal tissue with a spatial resolution as high as 10 5m when we complete the Phase II of this project. It has been well known that the magnetic field outside a conducting medium such as a bath filled with saline or the human head is solely due to currents tangential to the conducting boundary. In the case of human head, magnetoencephalography (MEG) measures only the currents tangential, but not radial, to the brain-air boundary. In the case of a neuronal tissue in a bath, the magnetic field is solely due to currents tangential, but not perpendicular, to bath surface. This fundamental limitation has restricted the use of biomagnetometry. In Phase I we will use the PRISM in a physical phantom to test whether the PRISM will make the vertically oriented currents in a bath "visible". When this mirror is submerged in a bath of physiological saline just above a neural tissue, it will produce the so- called secondary source oriented perpendicular to its surface when a population of neurons produces vertical or horizontal intracellular currents below the mirror. According to our simulation study, the horizontal component of the secondary source on the PRISM will make the vertical current "visible" to a magnetometer above the bath. We will compare the results with a realistic simulation study using a boundary element method to fully represent the experimental condition. We will further evaluate two important properties of this technique that may enable us to develop a high resolution scanning magnetometry in Phase II. We will test our claim that: (1) the spatial resolution primarily depends on the distance between the mirror and active neurons below, instead of the distance between the magnetic field sensing coils above the bath and the volume of active neurons, and (2) the spatial resolution is independent of the dection coil size (within reasonable limits). These results will enable us to develop a novel high-resolution scanning magnetometry in Phase II. PUBLIC HEALTH RELEVANCE: This simple, but novel invention will expand applications of magnetometry since it will enable us to obtain images of current distribution in biological tissues, containing currents in any directions with an unprecedent-ed level of spatial resolution. The scanning magnetometry should become an important new tool in bio-medical research in the area of direct high resolution imaging of electrical currents such as neural currents in biological tissues in vitro. This technique can be in principle applied to human MEG studies as well.