Age dependence of hemodynamic response characteristics in human functional magnetic resonance imaging
Age dependence of hemodynamic response characteristics in human functional magnetic resonance imaging
复制标题
DOI：
10.1016/j.neurobiolaging.2012.11.002
复制
发表时间：
2013-05-01
影响因子：
4.2
通讯作者：
Hoge, Richard D.
中科院分区：
文献类型：
--
作者：
Gauthier, Claudine J.;Madjar, Cecile;Hoge, Richard D.
认知衰老的功能磁共振成像（fMRI）研究通常比较了老年组和年轻组中一项任务引起的血氧水平依赖性（BOLD）信号增加的幅度和程度。因此，BOLD 被用作神经元激活的直接指标，并且假设神经元活动与血流动力学反应之间的关系在整个生命周期中保持不变。然而，即使在健康衰老的情况下，也观察到血管和代谢功能的差异可能会影响神经元活动和 BOLD 信号之间的耦合。在这里，我们使用校准的功能磁共振成像方法来探索可能使这种大胆比较产生偏差的血管和代谢变化。虽然认知任务引起的 BOLD 信号变化在年轻人和老年人组之间相似（例如，右额叶区域为 0.50 +/- 0.04% 对比 0.50 +/- 0.05%），但通过受控的全局高碳酸操作在同一组结构中引发的 BOLD 和动脉自旋标记 (ASL) 反应的比较显示两组之间存在显着差异。研究发现，老年人对高碳酸血症的 BOLD 反应和血流反应较低（例如，BOLD 灰质反应为 1.48 +/- 0.07% 与 1.01 +/- 0.06%，血流反应为 24.92 +/- 1.37% 与 20.67 +/- 2.58%），最大 BOLD 反应 M 普遍较低（5.76 +/- 0.2%）对比 5.00 +/- 0.3%）。这表明，与年轻群体中相同的 BOLD 反应相比，老年人中特定的 BOLD 反应可能代表着神经元活动更大的变化。这项研究的结果强调了当比较可能表现出血管生理学差异的人群的功能磁共振成像反应时，辅助测量（例如 ASL）对于正确解释 BOLD 反应的重要性。 (C) 2013 Elsevier Inc. 保留所有权利。
Functional magnetic resonance imaging (fMRI) studies of cognitive aging have generally compared the amplitude and extent of blood oxygen level-dependent (BOLD) signal increases evoked by a task in older and younger groups. BOLD is thus used as a direct index of neuronal activation and it is assumed that the relationship between neuronal activity and the hemodynamic response is unchanged across the lifespan. However, even in healthy aging, differences in vascular and metabolic function have been observed that could affect the coupling between neuronal activity and the BOLD signal. Here we use a calibrated fMRI method to explore vascular and metabolic changes that might bias such BOLD comparisons. Though BOLD signal changes evoked by a cognitive task were found to be similar between a group of younger and older adults (e. g., 0.50 +/- 0.04% vs. 0.50 +/- 0.05% in right frontal areas), comparison of BOLD and arterial spin labelling (ASL) responses elicited in the same set of structures by a controlled global hypercapnic manipulation revealed significant differences between the 2 groups. Older adults were found to have lower responses in BOLD and flow responses to hypercapnia (e.g., 1.48 +/- 0.07% vs. 1.01 +/- 0.06% over gray matter for BOLD and 24.92 +/- 1.37% vs. 20.67 +/- 2.58% for blood flow), and a generally lower maximal BOLD response M (5.76 +/- 0.2% vs. 5.00 +/- 0.3%). This suggests that a given BOLD response in the elderly might represent a larger change in neuronal activity than the same BOLD response in a younger cohort. The results of this study highlight the importance of ancillary measures such as ASL for the correct interpretation of BOLD responses when fMRI responses are compared across populations who might exhibit differences in vascular physiology. (C) 2013 Elsevier Inc. All rights reserved.