Contribution of Ultra Low Frequency LFPs to Functional MRI

描述(申请人提供)：静息状态磁共振成像(RsMRI)，基于血氧水平依赖(BOLD)信号的波动，越来越多地被用于绘制大脑中自发活动的网络图。这些波动的神经基础尚不清楚，各种研究报告与低频功率、高频功率、峰电流调制和血管运动有关。虽然大胆波动的频率范围是0-0.1赫兹，但之前的研究已经检查了更高频段的电活动(&gt；1赫兹)。然而，众所周知，次慢振荡存在于大脑中，它们与正常人和ADHD患者的注意力控制和反应时间的波动有关。我们假设，BOLD波动与同一频段内的电子波动有直接联系，并且这些较慢的振荡对较高频率的调制导致与BOLD信号的状态依赖关系。1.确定亚慢电位波动与典型LFP频段(1-100赫兹)活动之间的关系。将从皮质和皮质下部位网络记录IFSO和宽带局部场电位(LFP)，以确定IFSO的空间分布及其如何影响局部活动。同时的IFSO和细胞内记录将检查膜电位的变化是否与低频振荡有关。不同的麻醉状态会调节 神经活动。2.在逐个站点和网络的基础上，描述IFSO对粗放信号的贡献。还没有研究关注低频剧烈波动的直接频率相关性。初步数据表明，可以使用磁共振成像绘制IFSO的模式。使用我们实验室开发的同步记录/成像协议，我们将从目标1中检查的网络中选择站点获得LFP(宽带和次慢)和BOLD。LFP和本地BOLD信号之间的关联将被执行，以确定对BOLD波动的最大贡献，而带限LFP和BOLD关联之间的一致性将被比较，以确定BOLD关联的最佳预测因子。3.研究IFSO的时空动力学，并确定它们与准周期大胆波动的联系。初步数据表明，BOLD和IFSO之间的时滞相关性显示了一种沿大脑皮层传播的模式，这种模式与之前用BOLD信号观测到的时空动力学非常相似。这个目标将使用为目标1和目标2同时获取的多点数据来直接检查BOLD和IFSO动力学之间的联系。该项目将提供独特的洞察，了解以磁共振成像创建的功能连接图为基础的网络活动，如果我们的假设被证明是正确的，将导致一种新的方法来绘制次慢活动的时空模式，这种活动以脑电图学无法获得的分辨率调节整个大脑的注意力。

DESCRIPTION (provided by applicant): Resting state MRI (rsMRI), based on fluctuations in the blood oxygenation level dependent (BOLD) signal, is increasingly used to map networks of spontaneous activity in the brain. The neural basis of these fluctuations is not well understood, with various studies reporting a link to low frequency power, high frequency power, modulation of spiking, and vasomotion. While the frequency range of the BOLD fluctuations is 0-0.1 Hz, previous studies have examined electrical activity in higher frequency bands (>1 Hz). It is known, however, that infra-slow oscillations (IFSOs; <1 Hz) exist in the brain and they have been linked to fluctuations in attentional control and reaction time in normal subjects and ADHD patients. We hypothesize that the BOLD fluctuations have a direct link to electrical fluctuations in the same frequency band, and that the modulation of higher frequencies by these slower oscillations leads to state-dependent relationships with the BOLD signal. 1. Determine the relationship between infra-slow potential fluctuations and activity in typical LFP bands (1-100 Hz). IFSOs and broadband local field potentials (LFPs) will be recorded from a network of cortical and subcortical sites to determine the spatial distribution of IFSOs and how they affect local activity. Simultaneous IFSO and intracellular recording will examine whether membrane potential changes are tied to low frequency oscillations. Different anesthetic states will modulate neural activity. 2. Characterize the contribution of IFSOs to the BOLD signal on a site-by-site and network basis. No studies have looked at the direct frequency correlates of the low frequency BOLD fluctuations. Preliminary data suggests that patterns of IFSOs can be mapped using MRI. Using a simultaneous recording/imaging protocol developed in our lab, we will obtain LFPs (broadband and infra-slow) and BOLD from sites selected from the network examined in aim 1. Correlation between LFPs and local BOLD signal will be performed to determine the largest contribution to BOLD fluctuations, while coherence between band-limited LFPs and BOLD correlation will be compared to identify the best predictors of BOLD correlation. 3. Examine the spatiotemporal dynamics of IFSOs and determine their link to quasi-periodic BOLD fluctuations. Preliminary data indicates that the time-lagged correlation between BOLD and IFSOs demonstrates a pattern of propagation along the cortex that is highly similar to the spatiotemporal dynamics previously observed with the BOLD signal. This aim will directly examine the link between BOLD and IFSO dynamics using the simultaneously-acquired multi-site data collected for aims 1 and 2. This project will provide unique insight into the network activity that underlies functional connectivity maps created with MRI and, if our hypothesis proves correct, will lead to a new way to map the spatiotemporal patterns of the infra-slow activity that modulates attention throughout the whole brain with resolution unobtainable with electroencephalography.