Magnetic Resonance Imaging of Cortical Neuronal Activity

描述（由申请人提供）：自问世以来，使用血氧水平依赖（BOLD）对比度的功能性MRI（fMRI）在基础和临床神经科学中的应用出现了爆炸性增长，并继续成为神经成像的主要方法。然而，BOLD成像也遭受分散的空间定位和时间延迟，由于来自所有尺寸的脉管系统的血液动力学调制，并且仍然是神经元功能的某种定性评估。一直在努力提高BOLD对比度内的空间定位和时间分辨率。近年来，基于神经电活动的完全独立对比被提出和开发，并在体外和体内应用中显示出初步的前景。在这个提议中，我们将整合近年来血流动力学和神经电成像的进展，并开发一种直接的MRI方法，其中心重点是大幅提高神经电信号的灵敏度。具体而言，三个互补的目标，共同强调实现更大的灵敏度，但也与创新的成像硬件，成像软件和驱动的神经元振荡的个人重点，提出了实现离子神经电活动的直接MRI。首先，我们将开发一种新的多模式并行接收线圈，以实现高灵敏度、高分辨率、弥散对比成像，以改善与皮层神经元活动的空间对应性;其次，我们将开发一种螺旋回波容积成像（EVI）技术，以进一步提高成像灵敏度;第三、我们将开发直接MRI方法的离子神经电活动使用同步梯度振荡和高，频率驱动的视觉刺激，并结合在以前的目标的进展，以进一步获得急需的信噪比（SNR）的时间锁定的时间平均内的神经激活的区域。我们预计，我们的综合方法将允许最高的灵敏度来测量离子神经电信号，表征其空间和时间的依赖性，并显着走向一个直接和敏感的功能磁共振成像方法在体内成像皮层神经电活动。 公共卫生相关性：该项目是基于一个综合的方法来图像皮质神经元的活动，使用血流动力学和神经电对比。我们提出了三个具体的目标，以实现这一中心目标，所有的中心重点是大大提高灵敏度，但也有各自的重点，新的成像硬件，软件和创新的神经元激活范例。这三个目标的进展将使时间锁定检测离子神经电流与直接的空间和时间特异性。我们预计，我们的综合方法将使我们能够建立一个坚实的技术基础，朝着一个敏感的，非侵入性的，更重要的是，直接的神经成像方法。

DESCRIPTION (provided by applicant): Since its inception, functional MRI (fMRI) using blood oxygenation level dependent (BOLD) contrast has seen an explosive growth in its applications in basic and clinical neurosciences, and continues to be the dominant method in neuroimaging. However, BOLD imaging also suffers from dispersed spatial localizations and temporal delays due to hemodynamic modulations from vasculature of all sizes, and remains a somewhat qualitative assessment of neuronal functions. Continued effort has been made to improve the spatial localization and the temporal resolution within the BOLD contrast. In more recent years, completely independent contrasts based on neuroelectric activities have been proposed and developed, and have shown initial promises in applications in vitro and in vivo. In this proposal, we will integrate the advances of hemodynamic and neuroelectric imaging in the recent years, and develop a direct MRI approach with a central focus on drastically improving the sensitivity of the neuroelectric signal. Specifically, three complementing aims, with a common emphasis on achieving a much greater sensitivity, but also with individual focuses on innovative imaging hardware, imaging software and driven neuronal oscillations, are proposed to achieve a direct MRI of ionic neuroelectric activity. First, we will develop a new multi-mode parallel receive coil to achieve high-sensitivity, high-resolution, diffusion contrast imaging for improved spatial correspondence with cortical neuronal activities; Second, we will develop a spiral echo volume imaging (EVI) technique to further improve the imaging sensitivity; Third, we will develop direct MRI methodology of ionic neuroelectric activities using synchronized gradient oscillation and high-frequency driven visual stimulation, and in conjunction with advances in the previous aims, to further gain the much needed signal- to-noise ratio (SNR) by time-locked temporal averaging within the neuronally activated regions. We anticipate that our integrated approach will allow the highest sensitivity possible to measure ionic neuroelectric signals, characterize their spatial and temporal dependences, and move significantly toward a direct and sensitive fMRI methodology for imaging cortical neuroelectric activities in vivo. PUBLIC HEALTH RELEVANCE: This project is based on an integrated approach to image cortical neuronal activities using hemodynamic and neuroelectric contrasts. We propose three specific aims to achieve this central objective, all with a central focus for a greatly improved sensitivity, but also with respective focuses on new imaging hardware, software and innovative neuronal activation paradigms. The advances from these three aims will enable time-locked detection of ionic neuroelectric currents with direct spatial and temporal specificity. We anticipate that our integrated approach will allow us to establish a solid technical foundation toward a sensitive, non-invasive, and more importantly, direct neuroimaging methodology.