Wang Rong, Foniok Tadeusz, Wamsteeker Jaclyn I, Qiao Min, Tomanek Boguslaw, Vivanco Rodrigo A, Tuor Ursula I
Institute for Biodiagnostics (West), National Research Council of Canada, B153, 3330 Hospital DR N.W., Calgary, Alberta, Canada T2N4N1.
Neuroimage. 2006 May 15;31(1):1-11. doi: 10.1016/j.neuroimage.2005.12.004. Epub 2006 Feb 3.
Functional magnetic resonance imaging (fMRI) provides an indirect measure of cerebral activation that could be altered by factors directly affecting cerebral blood flow independent of changes in neuronal activation. Presently, we investigate how changes in blood pressure (BP) affect the activation detected with fMRI. fMRI scans were acquired in 33 rats under control conditions and following transient BP increases (norepinephrine, IV) or decreases (arfonad, IV) with and without electrical stimulation of the forepaw. Voxels correlating to either the stimulation or the change in BP time courses were identified. During transient hypertension, irrespective of forepaw stimulation, BP increases (i.e., >10 mm Hg) produced a transient increase in the blood oxygen level-dependent (BOLD) intensity resulting in a significant numbers of voxels correlating to the BP time courses (P < 0.05), and the number of these voxels increased as BP increased, becoming substantial at BP > 30 mm Hg. The activation patterns with BP increases and stimulation overlapped spatially resulting in an enhanced cerebral activation to simultaneous forepaw stimulation (P < 0.05). BP decreases (>10 mm Hg) produced corresponding decreases in BOLD intensity, causing significant numbers of voxels correlating to the BP decreases (P < 0.005), and these numbers increased as BP decreased (P < 0.001). The BP decreases and stimulation time courses and responses were distinct, and hypotension did not affect the detection of the activation response to forepaw stimulation. The results indicate that substantial hypertension accompanying a stimulation paradigm produces a BOLD response that enhances the cerebral activation detected, whereas hypotension does not affect the detection of neuronal activation but does produce responses that could be interpreted as a 'deactivation'.
功能磁共振成像（fMRI）提供了一种大脑激活的间接测量方法，这种测量可能会受到直接影响脑血流量的因素的改变，而与神经元激活的变化无关。目前，我们研究血压（BP）的变化如何影响fMRI检测到的激活情况。在33只大鼠中，在对照条件下以及在前爪接受或不接受电刺激的情况下，分别在血压短暂升高（静脉注射去甲肾上腺素）或降低（静脉注射阿方那特）后进行fMRI扫描。确定了与刺激或血压时间过程变化相关的体素。在短暂性高血压期间，无论前爪是否受到刺激，血压升高（即>10 mmHg）都会导致血氧水平依赖（BOLD）强度短暂增加，从而产生大量与血压时间过程相关的体素（P<0.05），并且随着血压升高，这些体素的数量增加，在血压>30 mmHg时变得显著。血压升高和刺激时的激活模式在空间上重叠，导致对同时进行的前爪刺激的大脑激活增强（P<0.05）。血压降低（>10 mmHg）会导致BOLD强度相应降低，产生大量与血压降低相关的体素（P<0.005），并且随着血压降低，这些体素的数量增加（P<0.001）。血压降低和刺激的时间过程及反应是不同的，低血压并不影响对前爪刺激激活反应的检测。结果表明，在刺激范式下伴随的显著高血压会产生一种BOLD反应，增强检测到的大脑激活，而低血压并不影响神经元激活的检测，但确实会产生可解释为“失活”的反应。
