Linear coupling of undershoot with BOLD response in ER-fMRI and nonlinear BOLD response in rapid-presentation ER-fMRI.
Linear coupling of undershoot with BOLD response in ER-fMRI and nonlinear BOLD response in rapid-presentation ER-fMRI.
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DOI：
10.1016/j.neuroimage.2011.04.067
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发表时间：
2011-07-15
期刊：
影响因子：
5.7
通讯作者：
Huang, Jie
中科院分区：
文献类型：
--
作者：
Zong, Xiaopeng;Huang, Jie
关键词：
在事件相关（ER） BOLD- fmri脑激活研究中，理解激发的BOLD信号与其潜在神经元活动之间的关系对于从BOLD测量中定量解释神经事件至关重要。这需要更好地理解BOLD的动态响应。除了神经元活动诱导的积极的BOLD反应外，动态反应的特征还包括刺激后的严重欠冲。然而，积极的反应和刺激后的不足之间的关系仍然知之甚少。早期的研究使用长刺激持续时间（10 ~ 10秒）的块设计范式，并没有提出定量关系。利用内质网范式，本研究揭示了积极的BOLD反应与刺激后欠冲之间的线性耦合。在内质网模式下，视觉皮层的体向线性耦合强有力地支持均匀的血流动力学反应，尽管BOLD反应的幅度在视觉皮层的大范围内变化很大。尽管潜在的神经元活动对BOLD反应负责，但血容量分数影响BOLD反应的大小；血容量分数越大，幅度越大。在对BOLD测量的任何定量解释中，都需要考虑到这种影响。在缺乏非线性神经元活动的情况下，非线性血管反应使得快速呈现（RP） ER模式下的估计BOLD反应比在ER模式下的估计BOLD反应更小，在解释RP-ER模式下的估计BOLD反应时也需要考虑这种减少效应。有趣的是，这种非线性效应可以简单地用视觉皮层的比例因子来解释。
In event-related (ER) BOLD-fMRI brain activation studies, understanding the relationship between the elicited BOLD signal and its underlying neuronal activity is essential for any quantitative interpretation of the neural events from the BOLD measurements. This requires a better understanding of the dynamic BOLD response. Besides the neuronal activity-induced positive BOLD response, the dynamic response is also characterized by a profound post-stimulus undershoot. The relationship between the positive response and the post-stimulus undershoot, however, remains poorly understood. Earlier studies using block-design paradigms with long stimulation durations (>10 s) do not suggest a quantitative relationship. Using an ER paradigm, this study revealed a linear coupling between the positive BOLD response and the post-stimulus undershoot across the human visual cortex. The voxelwise linear coupling across the visual cortex strongly supports a homogeneous hemodynamic response in ER paradigms, though the BOLD response magnitude varies substantially over a wide range across the visual cortex. Although underlying neuronal activity is responsible for a BOLD response, the blood volume fraction affects the magnitude of the BOLD response; the larger the blood volume fraction, the larger the magnitude. This effect needs to be accounted for in any quantitative interpretation of the BOLD measurements. In the absence of nonlinear neuronal activities, the nonlinear vascular response renders the estimated BOLD responses smaller in rapid presentation (RP) ER paradigms compared to that in ER paradigms, and this reduction effect also needs to be considered when interpreting the estimated BOLD responses in RP-ER paradigms. Interestingly, this nonlinear effect might be simply accounted for by a scaling factor across the visual cortex.
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影响因子：
3.3
作者：
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期刊：
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通讯作者：
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影响因子：
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