Age-related differences in cerebral blood flow underlie the BOLD fMRI signal in childhood.
Age-related differences in cerebral blood flow underlie the BOLD fMRI signal in childhood.
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DOI：
10.3389/fpsyg.2014.00300
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发表时间：
2014
影响因子：
3.8
通讯作者：
Orient E
中科院分区：
文献类型：
--
作者：
Moses P;Hernandez LM;Orient E
功能磁共振成像（fMRI）已成为研究儿童广泛的典型和非典型行为的发展和神经介导的首要技术。虽然血氧水平依赖（BOLD）的功能磁共振成像信号的机制一直是研究的重点，在成熟的大脑，它一直在很大程度上未在发育中的大脑检查。BOLD信号的一个重要组成部分是脑血流量（CBF），它已被注意到随年龄而变化。基于临床放射性示踪方法的儿童CBF报告发现儿童期CBF相对于成年期升高，这可能影响BOLD反应。本研究使用非侵入性动脉自旋标记磁共振成像研究静息状态和活动驱动的CBF与功能BOLD反应在健康儿童8和12岁和成人。参与者进行了一项手指敲击任务，以产生在运动皮层中测量的强大激活。静息状态CBF的定量显示8奥尔兹和12岁儿童的CBF相对于成人较高。在运动任务期间，两个儿童组的基线休息和峰值反应之间的CBF绝对增加也高于成人。相比之下，各组CBF相对于基线的相对增加（以CBF变化百分比表示）相当。BOLD信号变化的百分比在各年龄组中也是稳定的。这组发现表明，沿着儿童期CBF升高，BOLD反应的其他组成过程也处于升高状态，从而共同产生类似于成人的净BOLD效应。这些发现与我们先前对初级感觉皮层血流动力学的研究相吻合。虽然BOLD反应的幅度在儿童和成年之间似乎是一致的，但引起BOLD效应的潜在生理学和脑血管动力学在不成熟和成熟的神经系统之间是不同的。
Functional magnetic resonance imaging (fMRI) has become a premiere technique for studying the development and neural mediation of a wide range of typical and atypical behaviors in children. While the mechanism of the blood oxygen level-dependent (BOLD) fMRI signal has been a focus of investigation in the mature brain, it has been largely unexamined in the developing brain. One critical component of the BOLD signal that has been noted to change with age is cerebral blood flow (CBF). Reports of CBF in children based on clinical radioactive tracing methods have found elevated CBF in childhood relative to adulthood, which could affect the BOLD response. This study used non-invasive arterial spin labeling magnetic resonance imaging to study resting state and activity-driven CBF in conjunction with the functional BOLD response in healthy children 8 and 12 years of age and in adults. Participants performed a finger-tapping task to generate robust activation measured in the motor cortex. Quantification of resting state CBF demonstrated higher CBF in 8 year olds and in 12 year olds relative to adults. The absolute increase in CBF between baseline rest and peak response during the motor task was also higher in both child groups compared to adults. In contrast, the relative increase of CBF above baseline, expressed as percent of CBF change, was comparable across groups. The percent of BOLD signal change was also stable across age groups. This set of findings suggests that along with elevated CBF in childhood, other component processes of the BOLD response are also in an elevated state such that together they yield a net BOLD effect that resembles adults. These findings coincide with our previous examination of hemodynamics in primary sensory cortex. Although the magnitude of the BOLD response appears consistent between childhood and adulthood, the underlying physiology and cerebrovascular dynamics that give rise to the BOLD effect differ between immature and mature neural systems.
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