Liu Xueqing, Gerraty Raphael T, Grinband Jack, Parker David, Razlighi Qolamreza R
Biomedical Engineering Department, Columbia University, New York, New York, United States.
Department of Psychology, Columbia University, New York, New York, United States.
Hum Brain Mapp. 2017 Jul;38(7):3402-3414. doi: 10.1002/hbm.23597. Epub 2017 Apr 11.
Use of functional magnetic resonance imaging (fMRI) in studies of aging is often hampered by uncertainty about age-related differences in the amplitude and timing of the blood oxygenation level dependent (BOLD) response (i.e., hemodynamic impulse response function (HRF)). Such uncertainty introduces a significant challenge in the interpretation of the fMRI results. Even though this issue has been extensively investigated in the field of neuroimaging, there is currently no consensus about the existence and potential sources of age-related hemodynamic alterations. Using an event-related fMRI experiment with two robust and well-studied stimuli (visual and auditory), we detected a significant age-related difference in the amplitude of response to auditory stimulus. Accounting for brain atrophy by circumventing spatial normalization and processing the data in subjects' native space eliminated these observed differences. In addition, we simulated fMRI data using age differences in brain morphology while controlling HRF shape. Analyzing these simulated fMRI data using standard image processing resulted in differences in HRF amplitude, which were eliminated when the data were analyzed in subjects' native space. Our results indicate that age-related atrophy introduces inaccuracy in co-registration to standard space, which subsequently appears as attenuation in BOLD response amplitude. Our finding could explain some of the existing contradictory reports regarding age-related differences in the fMRI BOLD responses. Hum Brain Mapp 38:3402-3414, 2017. © 2017 Wiley Periodicals, Inc.
在衰老研究中，功能磁共振成像（fMRI）的应用常常受到阻碍，原因在于血氧水平依赖（BOLD）反应（即血流动力学脉冲响应函数（HRF））的幅度和时间方面与年龄相关的差异存在不确定性。这种不确定性给fMRI结果的解读带来了重大挑战。尽管这一问题在神经成像领域已得到广泛研究，但目前对于与年龄相关的血流动力学改变的存在及潜在来源尚无共识。通过一项事件相关fMRI实验，采用两种经过充分研究且可靠的刺激（视觉和听觉），我们检测到对听觉刺激的反应幅度存在显著的年龄相关差异。通过规避空间归一化并在受试者的原始空间中处理数据来考虑脑萎缩，消除了这些观察到的差异。此外，我们在控制HRF形状的同时，利用脑形态学的年龄差异模拟了fMRI数据。使用标准图像处理分析这些模拟的fMRI数据会导致HRF幅度出现差异，而在受试者的原始空间中分析数据时这些差异会被消除。我们的结果表明，与年龄相关的萎缩在与标准空间的配准中引入了不准确性，这随后表现为BOLD反应幅度的衰减。我们的发现可以解释一些关于fMRI BOLD反应中与年龄相关差异的现有矛盾报道。《人类大脑图谱》38:3402 - 3414, 2017。© 2017威利期刊公司。
