Variability of the coupling of blood flow and oxygen metabolism responses in the brain: a problem for interpreting BOLD studies but potentially a new window on the underlying neural activity
Variability of the coupling of blood flow and oxygen metabolism responses in the brain: a problem for interpreting BOLD studies but potentially a new window on the underlying neural activity
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DOI：
10.3389/fnins.2014.00139
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发表时间：
2014-06-11
影响因子：
4.3
通讯作者：
Moradi, Farshad
中科院分区：
文献类型：
--
作者：
Buxton, Richard B.;Griffeth, Valerie E. M.;Moradi, Farshad
最近，我们和其他人使用定量fMRI方法的研究发现，对刺激的血流（CBF）和氧代谢（CMRO 2）反应的耦合比的变化对BOLD反应有很强的影响。在许多研究中，CBF和CMRO 2变化与神经激活相结合的方式正在出现一种经验模式：如果刺激被调制以产生更强的反应（例如，增加刺激对比度），则CBF比CMRO 2被更多地调节;另一方面，如果改变大脑状态使得对相同刺激的响应增加（例如，由于CBF和CMRO 2的变化在产生BOLD信号变化方面存在冲突，因此这一发现对传统的BOLD-fMRI研究具有重要意义：BOLD反应夸大了刺激变化的影响，但对改变对标准刺激反应的大脑状态的调制仅具有微弱的敏感性。一个推测性的假设是，CBF和CMRO 2反应的耦合比的可变性反映了不同比例的抑制性和兴奋性诱发活动，可能提供了一个新的窗口在人脑中的神经活动。
Recent studies from our group and others using quantitative fMRI methods have found that variations of the coupling ratio of blood flow (CBF) and oxygen metabolism (CMRO2) responses to a stimulus have a strong effect on the BOLD response. Across a number of studies an empirical pattern is emerging in the way CBF and CMRO2 changes are coupled to neural activation: if the stimulus is modulated to create a stronger response (e.g., increasing stimulus contrast), CBF is modulated more than CMRO2; on the other hand, if the brain state is altered such that the response to the same stimulus is increased (e.g., modulating attention, adaptation, or excitability), CMRO2 is modulated more than CBE Because CBF and CMRO2 changes conflict in producing BOLD signal changes, this finding has an important implication for conventional BOLD-fMRI studies: the BOLD response exaggerates the effects of stimulus variation but is only weakly sensitive to modulations of the brain state that alter the response to a standard stimulus. A speculative hypothesis is that variability of the coupling ratio of the CBF and CMRO2 responses reflects different proportions of inhibitory and excitatory evoked activity, potentially providing a new window on neural activity in the human brain.