Manipulation and characterization of functional connectivity measured with MRI

描述（由申请人提供）：功能磁共振成像（fMRI）对人脑血流动力学波动敏感。通过计算不同大脑区域波动之间的相关性而绘制的功能连通性图显示，在已知的强连接区域中存在高度相关性。这种相关性被认为与协调的神经活动有关。这项技术越来越多地用于探测正常受试者和神经系统疾病患者的大脑活动网络。然而，血液动力学波动的生理基础及其与潜在神经活动的联系尚不清楚。我们研究的最终目标是明确建立MRI测量的功能连接与神经活动之间的关系。在人类中很难探测两者之间的关系，迄今为止在动物身上进行的功能连接研究也很少。本研究拟采用微电极记录与成像相结合的方法，阐明MRI相关信号波动与神经活动的关系。图像之间会进行记录，这样就可以直接比较电相干性和MRI相关性。该建议的具体目的是：通过交叉微电极记录和图像采集在啮齿动物模型中确定功能连接和神经活动之间的关系。使用灌注、血氧和血容量加权MRI测量大鼠的功能连通性，以确定哪个血管特性是信号波动的主要来源。将诱导高碳酸血症来确定它是否会像在人类研究中那样抑制连通性。将记录呼吸和心脏周期，以确定它们对相关性的贡献。当麻醉水平改变神经活动时，局部场电位的记录和MRI图像的获取将交错进行，并将计算每对电极记录的一致性，并将其与MRI观察到的相关性进行比较。这个项目的目标是确定功能连接和神经活动之间的关系。这是我们长期目标的第一步，即建立功能连接映射作为临床神经系统疾病诊断和评估的非侵入性工具。该项目的目标是确定用MRI测量的啮齿动物的功能连通性与潜在的神经活动之间的关系。这是我们长期目标的第一步，即建立功能连接映射作为临床神经系统疾病诊断和评估的非侵入性工具。

Description (provided by applicant): Functional magnetic resonance imaging (fMRI) is sensitive to hemodynamic fluctuations in the human brain. Functional connectivity maps created by calculating the correlation between fluctuations from different brain areas show high correlation in areas that are known to be strongly connected. The correlation is presumed to be related to coordinated neural activity. This technique is increasingly used to probe networks of brain activity in both normal subjects and patients with neurological disorders. However, the physiological basis of the hemodynamic fluctuations and the connection to underlying neural activity are not well understood. The ultimate goal of our research is to definitively establish the relationship between functional connectivity measured with MRI and neural activity. It is difficult to probe the relationship between the two in humans, and few functional connectivity studies have been performed in animals to date. This study proposes to elucidate the relationship between correlated MRI signal fluctuations and neural activity by combining microelectrode recording and imaging in the rodent. Recording will occur between images, so that electrical coherence and MRI correlations can be directly compared. The specific aim of this proposal is: Determine the relationship between functional connectivity and neural activity by interleaving microelectrode recordings and image acquisition in a rodent model.: Functional connectivity will be measured in rats using perfusion, blood oxygenation, and blood-volume weighted MRI to identify which vascular property is the predominant source of signal fluctuations. Hypercapnia will be induced to determine whether it suppresses connectivity as in human studies. Respiratory and cardiac cycles will be recorded to determine their contributions to correlation. Recording of local field potentials and acquisition of MRI images will be interleaved and acquired as anesthesia level is varied to alter neural activity, and coherence in recordings from each pair of electrodes will be calculated and compared to correlation observed with MRI. The goal of this project is to determine the relationship between functional connectivity and neural activity. This is the first step toward our long-term goal of establishing functional connectivity mapping as a noninvasive tool for the diagnosis and evaluation of clinical neurological disorders. PUBLIC HEALTH RELEVANCE The goal of this project is to determine the relationship between functional connectivity measured with MRI in the rodent and the underlying neural activity. This is the first step toward our long-term goal of establishing functional connectivity mapping as a noninvasive tool for the diagnosis and evaluation of clinical neurological disorders.