High Resolution Scanning Magnetometry

描述（由申请人提供）：在第一阶段，我们建议测试基于简单但新颖的主源镜（PRISM）概念开发用于神经科学的高分辨率扫描磁力测定法的可行性。PRISM可以有不同的设计，但在本项目中，它将是一个充气玻璃移液管，末端有一个小玻璃板，向底部倾斜45 °。我们声称，这面镜子可以用来可视化的电流分布，无论源的方向在体外神经元组织的空间分辨率高达10 - 5米，当我们完成该项目的第二阶段。众所周知，导电介质（如充满盐水的浴缸或人体头部）外部的磁场仅是由于与导电边界相切的电流引起的。在人类头部的情况下，脑磁图（MEG）仅测量与大脑-空气边界相切的电流，而不是径向电流。在神经元组织处于浴槽中的情况下，磁场仅仅是由于与浴槽表面相切而非垂直的电流。这一基本限制限制了生物磁测量的使用。在第一阶段，我们将使用PRISM在一个物理体模，以测试是否PRISM将使垂直方向的电流在一个浴“可见”。当这面镜子被浸没在生理盐水浴中，正好在神经组织上方时，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，它将产生垂直于其表面定向的所谓次级源。根据我们的模拟研究，PRISM上次级源的水平分量将使垂直电流对浴上方的磁力计“可见”。我们将使用边界元法完全代表实验条件的现实模拟研究的结果进行比较。我们将进一步评估这种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力测量。我们将测试我们的主张：（1）空间分辨率主要取决于镜子和下面的活动神经元之间的距离，而不是浴上方的磁场感测线圈之间的距离和活动神经元的体积，以及（2）空间分辨率与检测线圈大小无关（在合理的范围内）。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力仪。 公共卫生相关性：这个简单但新颖的发明将扩展磁力测量的应用，因为它将使我们能够获得生物组织中电流分布的图像，包含具有前所未有的空间分辨率水平的任何方向的电流。在生物医学研究中，扫描磁测法应成为一种重要的新工具，在该领域中的电流，如神经电流在体外生物组织中的直接高分辨率成像。该技术原则上也可应用于人类脑磁图研究。

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.