DYNAMIC MAGNETIC-RESONANCE-IMAGING OF HUMAN BRAIN ACTIVITY DURING PRIMARY SENSORY STIMULATION
DYNAMIC MAGNETIC-RESONANCE-IMAGING OF HUMAN BRAIN ACTIVITY DURING PRIMARY SENSORY STIMULATION
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DOI：
10.1073/pnas.89.12.5675
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发表时间：
1992-06-15
影响因子：
11.1
通讯作者：
ROSEN, BR
中科院分区：
文献类型：
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作者：
KWONG, KK;BELLIVEAU, JW;ROSEN, BR
神经元活动引起局部脑血流量、血容量和血氧水平的变化。磁共振成像(MRI)技术是通过高速回波平面成像发展起来的，它能敏感地反映脑血流和血氧的变化。这些技术被用来通过使用视觉和运动刺激范例来获得完全非侵入性的人脑活动断层扫描图。使用对脱氧血红蛋白顺磁状态敏感的梯度回波(GE)成像序列检测血液氧合的变化。血流变化通过自旋回波反转恢复(IR)，组织松弛参数T1敏感的脉冲序列来评估。在任务激活过程中，使用相同的成像脉冲序列(GE或IR)连续采集一系列图像。减影图像的电影显示(激活减去基线)直接显示了在时间分辨率为秒的情况下观察到的活动诱导的大脑MR信号的变化。在8赫兹图形闪光刺激下，7名正常志愿者的初级视皮层(V1)的信号强度显著增加(配对t检验；P<；0.001)，分别为1.8%+/-0.8%(GE)和1.8%+/-0.9%(IR)。信号变化的平均上升时间常数：GE图像为4.4±-2.2 S，红外图像为8.9±2.8 S。视觉激活的刺激频率依赖性与之前的正电子发射断层扫描观察结果一致，最大的MR信号响应出现在8赫兹。在挤压手的任务和高碳酸血症增加血流的动物模型中，人类初级运动皮质(ML)中也观察到了类似的信号变化。通过使用内在的血液-组织对比，功能磁共振打开了一扇了解个体大脑生理的时空窗口。
Neuronal activity causes local changes in cerebral blood flow, blood volume, and blood oxygenation. Magnetic resonance imaging (MRI) techniques sensitive to changes in cerebral blood flow and blood oxygenation were developed by high-speed echo planar imaging. These techniques were used to obtain completely noninvasive tomographic maps of human brain activity, by using visual and motor stimulus paradigms. Changes in blood oxygenation were detected by using a gradient echo (GE) imaging sequence sensitive to the paramagnetic state of deoxygenated hemoglobin. Blood flow changes were evaluated by a spin-echo inversion recovery (IR), tissue relaxation parameter T1-sensitive pulse sequence. A series of images were acquired continuously with the same imaging pulse sequence (either GE or IR) during task activation. Cine display of subtraction images (activated minus baseline) directly demonstrates activity-induced changes in brain MR signal observed at a temporal resolution of seconds. During 8-Hz patterned-flash photic stimulation, a significant increase in signal intensity (paired t test; P < 0.001) of 1.8% +/- 0.8% (GE) and 1.8% +/- 0.9% (IR) was observed in the primary visual cortex (V1) of seven normal volunteers. The mean rise-time constant of the signal change was 4.4 +/- 2.2 s for the GE images and 8.9 +/- 2.8 s for the IR images. The stimulation frequency dependence of visual activation agrees with previous positron emission tomography observations, with the largest MR signal response occurring at 8 Hz. Similar signal changes were observed within the human primary motor cortex (Ml) during a hand squeezing task and in animal models of increased blood flow by hypercapnia. By using intrinsic blood-tissue contrast, functional MRI opens a spatial-temporal window onto individual brain physiology.