Characteristics of perfusion related cortical signals

健康和疾病中的功能激活研究通常依赖于与灌流相关的信号来定位大脑活动的来源。该方案的目的是研究在各种刺激条件下使用光学本征信号(OIS)、近红外光谱(NIRS)、功能磁共振成像(FMRI)和脑电(EEG)测量的与血流灌注相关的信号。在动物和人类中应用不同的神经成像技术将全面了解这些与灌注相关的信号的时间、分布和容量，以及来自不同模式的与灌注相关的信号是如何相关的。我们将使用OIS(多光谱和单波长)、近红外光谱、功能磁共振成像、荧光染料和电测量来进行功能激活研究，以确定这些依赖于血流的诱发电位图之间的空间和时间关系。拟议的实验将提供对一连串事件的更好理解，这些事件统称为血液动力学反应。我们将在啮齿动物和人类的不同感觉系统中使用各种刺激和行为范式来完成这项工作。在人类中，使用OIS和电生理方法在术中获得的灌注相关信号将与相同受试者的NIRS和fMRI进行比较。在这两个物种中，图像配准后，将在受试者内部和受试者之间比较从每种模式获得的地图和反应的时间分布。拟议的研究将从调查一氧化氮(NO)在介导与灌流相关的反应中的作用开始。我们还将使用光学光谱学来表征功能性激活后的功能性血红蛋白变化的性质。在表征了功能性灌流相关反应的正常特征后，我们将确定灌流相关信号如何受到各种挑战的影响(包括癫痫发作、皮质扩散抑制、发育和经验依赖性可塑性)。最后，我们将调查和比较多种模式下的血流灌注相关信号之间的关系。这项建议是我们主动拨款的自然延伸，我们的重点是表征光信号对周围躯体感觉刺激反应的基本时间和空间特征。由于脑功能与脑灌注的耦合为许多功能神经成像技术提供了基础，因此对其具体的潜在生理机制及其特征的精确了解是至关重要的。这里描述的实验将帮助我们实现这一目标。

Functional activation studies in health and disease often depend upon perfusion related signals to localize the source of brain activity. The goal of this proposal is to investigate perfusion related signals measured using Optical Intrinsic Signals (OIS), Near Infrared Spectroscopy (NIRS), functional Magnetic Resonance Imaging (fMRI) and Electroencephalography (EEG) during a variety of stimulus conditions. The application of different neuroimaging techniques in both animals and humans will provide a comprehensive view of the timing, distribution and capacities of these perfusion related signals and how perfusion related signals from different modalities relate. We will perform functional activation studies using OIS (multispectral and single wavelength), NIRS, fMRI, fluorescent dyes and electrical measures, to determine the relationship in space and time between these perfusion dependent, and evoked potential maps. The proposed experiments will provide a better understanding of the cascade of events collectively called the hemodynamic response. We will do this in different sensory systems of rodents and humans using a variety of stimulus and behavioral paradigms. In humans, perfusion related signals obtained using OIS and electrophysiologic methods intraoperatively will be compared with NIRS and fMRI in the same subjects. In both species, maps and the temporal profile of responses obtained from each modality will be compared within and across subjects following image registration. The proposed studies will begin with investigating the role of nitric oxide (NO) in mediating perfusion related responses. We will also characterize the nature of functional hemoglobin changes following functional activation using optical spectroscopy. Having characterized the normal characteristics of functional perfusion related responses, we will then determine how perfusion related signals are affected by various challenges (including seizure, cortical spreading depression, development, and experience- dependent plasticity). Finally, we will investigate and compare the relationship between perfusion related signals across multiple modalities. This proposal is a natural extension to our active grant where the focus was to characterize the basic temporal and spatial characteristics of optical signal responses to peripheral somesthetic stimulation. Since the coupling of brain function to cerebral perfusion provides the basis for a number of functional neuroimaging techniques, a precise knowledge of the specific underlying physiological mechanisms and their characteristics is essential. The experiments described here will help us achieve that goal.