Origins of the BOLD post-stimulus undershoot
Origins of the BOLD post-stimulus undershoot
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DOI：
10.1016/j.neuroimage.2009.03.015
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发表时间：
2009-07-01
期刊：
影响因子：
5.7
通讯作者：
Pike, G. Bruce
中科院分区：
文献类型：
--
作者：
Chen, Jean J.;Pike, G. Bruce
血氧水平依赖（BOLD）刺激后负向偏移的解释一直是备受关注的课题，因为这种显著的BOLD瞬态背后的机制可能为大脑的神经血管反应过程和能量供应途径提供有价值的线索。生物力学理论通过毛细血管后血管的被动膨胀来解释BOLD负向偏移的起源，这种膨胀导致静脉血容量增加（CBVv，包括毛细血管、小静脉和小动脉腔室中的脱氧血），从而引起磁化率诱导的信号降低。虽然有大量证据支持静脉膨胀的作用，但也有报道认为刺激后脑氧消耗（CMRo₂）的持续升高是主要原因。此外，刺激后脑血流（CBF）负向偏移的作用也已得到证实。为了阐明静脉腔在导致BOLD负向偏移中的作用，我们对健康人进行了体内功能性磁共振成像（fMRI）测量，测量了瞬态ΔCBVv、ΔCBF和ΔBOLD反应。我们观察到静脉CBV在刺激后缓慢恢复到基线，这支持了被动“气球”效应的存在，意味着先前观察到的总CBV反应更快恢复可能主要是由动脉CBV变化引起的。我们的研究结果也支持CBF负向偏移的显著作用，它与缓慢的静脉CBV反应相结合，可以解释大部分的BOLD负向偏移。（C）2009爱思唯尔公司。保留所有权利。
The interpretation of the blood-oxygenation level-dependent (BOLD) post-stimulus undershoot has been a topic of considerable interest, as the mechanisms behind this prominent BOLD transient may provide valuable clues on the neurovascular response process and energy Supply routes of the brain. Biomechanical theories explain the origin of the BOLD undershoot through the passive ballooning of post-capillary vessels which leads to an increase in venous blood volume (CBVv, comprising deoxygenated blood in capillary, venular and arteriolar compartments), resulting in susceptibility-induced signal decrease. While there has been substantial evidence supporting a role for venous ballooning, there have also been reports arguing for a prolonged post-stimulus elevation in cerebral oxygenation consumption (CMRo(2)) as the primary cause. Furthermore, a contribution of post-stimulus cerebral blood flow (CBF) undershoots has also been demonstrated. To clarify the role of the venous compartment in causing the BOLD undershoot, we performed in vivo fMRI measurements of the transient Delta CBVv, Delta CBF and Delta BOLD responses in healthy humans. We observed a slow post-stimulus return to baseline in venous CBV which supports the existence of a passive "balloon" effect, implying that previous observations of a quicker recovery of the total CBV response may be dominated by arterial CBV change. Our findings also support a significant contribution from the CBF undershoots, which, combined with a slow venous CBV response, would account for Much of the BOLD undershoot. (C) 2009 Elsevier Inc. All rights reserved.