Miller K L, Luh W M, Liu T T, Martinez A, Obata T, Wong E C, Frank L R, Buxton R B
Department of Electrical Engineering, Stanford University, Stanford, California, USA.
Hum Brain Mapp. 2001 May;13(1):1-12. doi: 10.1002/hbm.1020.
The linearity of the cerebral perfusion response relative to stimulus duration is an important consideration in the characterization of the relationship between regional cerebral blood flow (CBF), cerebral metabolism, and the blood oxygenation level dependent (BOLD) signal. It is also a critical component in the design and analysis of functional neuroimaging studies. To study the linearity of the CBF response to different duration stimuli, the perfusion response in primary motor and visual cortices was measured during stimulation using an arterial spin labeling technique with magnetic resonance imaging (MRI) that allows simultaneous measurement of CBF and BOLD changes. In each study, the perfusion response was measured for stimuli lasting 2, 6, and 18 sec. The CBF response was found in general to be nonlinearly related to stimulus duration, although the strength of nonlinearity varied between the motor and visual cortices. In contrast, the BOLD response was found to be strongly nonlinear in both regions studied, in agreement with previous findings. The observed nonlinearities are consistent with a model with a nonlinear step from stimulus to neural activity, a linear step from neural activity to CBF change, and a nonlinear step from CBF change to BOLD signal change.
相对于刺激持续时间而言，脑灌注反应的线性在表征局部脑血流量（CBF）、脑代谢以及血氧水平依赖（BOLD）信号之间的关系时是一个重要的考量因素。它也是功能神经影像学研究的设计与分析中的一个关键组成部分。为了研究CBF对不同持续时间刺激的反应的线性，在刺激过程中，使用动脉自旋标记技术结合磁共振成像（MRI）来测量初级运动皮层和视觉皮层的灌注反应，该技术能够同时测量CBF和BOLD变化。在每项研究中，针对持续2秒、6秒和18秒的刺激测量灌注反应。尽管运动皮层和视觉皮层之间非线性的强度有所不同，但总体上发现CBF反应与刺激持续时间呈非线性相关。相比之下，在所研究的两个区域中均发现BOLD反应具有强烈的非线性，这与先前的研究结果一致。观察到的非线性与一个模型相符，该模型包括从刺激到神经活动的非线性步骤、从神经活动到CBF变化的线性步骤以及从CBF变化到BOLD信号变化 的非线性步骤。
