Auer Dorothee P
Academic Radiology, Queen's Medical Centre, University of Nottingham, Nottingham, UK.
Magn Reson Imaging. 2008 Sep;26(7):1055-64. doi: 10.1016/j.mri.2008.05.008. Epub 2008 Jul 26.
Functional magnetic resonance imaging techniques using the blood oxygenation level-dependent (BOLD) contrast are widely used to map human brain function by relating local hemodynamic responses to neuronal stimuli compared to control conditions. There is increasing interest in spontaneous cerebral BOLD fluctuations that are prominent in the low-frequency range (<0.1 Hz) and show intriguing spatio-temporal correlations in functional networks. The nature of these signal fluctuations remains unclear, but there is accumulating evidence for a neural basis opening exciting new avenues to study human brain function and its connectivity at rest. Moreover, an increasing number of patient studies report disease-dependent variation in the amplitude and spatial coherence of low-frequency BOLD fluctuations (LFBF) that may afford greater diagnostic sensitivity and easier clinical applicability than standard fMRI. The main disadvantage of this emerging tool relates to physiological (respiratory, cardiac and vasomotion) and motion confounds that are challenging to disentangle requiring thorough preprocessing. Technical aspects of functional connectivity fMRI analysis and the neuroscientific potential of spontaneous LFBF in the default mode and other resting-state networks have been recently reviewed. This review will give an update on the current knowledge of the nature of LFBF, their relation to physiological confounds and potential for clinical diagnostic and pharmacological studies.
使用血氧水平依赖（BOLD）对比的功能磁共振成像技术被广泛用于绘制人类大脑功能图，通过将局部血液动力学反应与对照条件下的神经元刺激相关联来实现。人们对自发的大脑BOLD波动越来越感兴趣，这种波动在低频范围（<0.1 Hz）很突出，并且在功能网络中表现出有趣的时空相关性。这些信号波动的本质仍不清楚，但越来越多的证据表明其存在神经基础，为研究静息状态下的人类大脑功能及其连通性开辟了令人兴奋的新途径。此外，越来越多的患者研究报告了低频BOLD波动（LFBF）的幅度和空间相干性存在疾病依赖性变化，这可能比标准功能磁共振成像具有更高的诊断敏感性和更易于临床应用。这种新兴工具的主要缺点与生理（呼吸、心脏和血管运动）和运动干扰有关，这些干扰难以区分，需要进行彻底的预处理。最近已经对功能连接性功能磁共振成像分析的技术方面以及默认模式和其他静息状态网络中自发LFBF的神经科学潜力进行了综述。本综述将更新关于LFBF本质的当前知识、它们与生理干扰的关系以及临床诊断和药理学研究的潜力。
