Neurophysiological Basis of fMRI

描述（由申请人提供）：功能性磁共振成像（fMRI）有望在完整受试者的正常操作过程中，提供精确定位和跟踪潜在的感觉、运动和认知技能的大脑活动模式的能力。然而，由于我们对神经活动和功能磁共振成像信号之间联系的理解不足，以及当前功能磁共振成像方法的固有局限性，这一前景受到了阻碍。我们将通过高场功能磁共振成像与猴神经系统电生理学和药理学相结合的实验来研究功能磁共振成像信号的神经基础；fMRI将使用高分辨率、高信噪比7特斯拉系统，采用BOLD和灌注敏感协议进行。电生理学将利用头皮ERP记录和线性阵列多电极深度记录，并将重点放在ERP和电流源密度（CSD）测量以及动作电位上。特别是CSD测量，对于连接神经活动和功能磁共振成像至关重要。神经化学操作将需要全身输注和皮质内微输注。我们的具体目标是：

DESCRIPTION (provided by applicant): Functional magnetic resonance imaging (fMRI) promises to provide the ability to pinpoint and track brain activity patterns underlying sensory, motor and cognitive skills, during their normal operation in intact subjects. However, this promise is thwarted by our inadequate understanding of the linkage between neural activity and fMRI signals, and by inherent limitations of current fMRI methods. We will investigate the neural basis of fMRI signals through experiments that combine high field fMRI with neural ensemble electrophysiology and pharmacology in monkeys; fMRI will be conducted with BOLD- and perfusion-sensitive protocols using a high-resolution, high signal-to-noise 7-Tesla system. Electrophysiology will utilize both scalp ERP recordings, and depth recordings with linear array multielectrodes, and will focus on ERP and current source density (CSD) measures as well as action potentials. CSD measures in particular, are essential for linking neural activity and fMRI. Neurochemical manipulation will entail both systemic infusions and intracortical microinfusions. Our specific aims are: 1. To Identify Neural Correlates of BOLD-fMRI: 2. To Optimize the Spatial and Temporal Resolution of fMRI 3. To Determine the Relationship of fMRI to ERPs and to Brain Processes. Initial studies will be conducted in anesthetized macaque monkeys & will focus on the cortical hand representation in Area 3b. Later studies will be implemented in awake monkeys & will be expanded to a few additional cortical regions. These studies will have the useful by-product of accurately describing the spatiotemporal activation pattern of the ascending somatosensory pathways from the hand surface in the macaque, and of doing so with methods that directly compare to those used in humans. This will help to bridge-the-gap between a vast single unit literature in monkeys, and a developing understanding of somatosensory structure and function in humans.