Yücel Meryem A, Selb Juliette, Aasted Christopher M, Lin Pei-Yi, Borsook David, Becerra Lino, Boas David A
MGH/HST Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital (MGH), Harvard Medical School, Charlestown, MA, USA.
Center for Pain and the Brain, Departments of Anaesthesia and Radiology, Boston Children's Hospital, Boston, MA, USA.
Biomed Opt Express. 2016 Jul 22;7(8):3078-88. doi: 10.1364/BOE.7.003078. eCollection 2016 Aug 1.
Analysis of cerebral hemodynamics reveals a wide spectrum of oscillations ranging from 0.0095 to 2 Hz. While most of these oscillations can be filtered out during analysis of functional near-infrared spectroscopy (fNIRS) signals when estimating stimulus evoked hemodynamic responses, oscillations around 0.1 Hz are an exception. This is due to the fact that they share a common spectral range with typical stimulus evoked hemodynamic responses from the brain. Here we investigate the effect of hemodynamic oscillations around 0.1 Hz on the estimation of hemodynamic response functions from fNIRS data. Our results show that for an expected response of ~1 µM in oxygenated hemoglobin concentration (HbO), Mayer wave oscillations with an amplitude > ~1 µM at 0.1 Hz reduce the accuracy of the estimated response as quantified by a 3 fold increase in the mean squared error and decrease in correlation (R(2) below 0.78) when compared to the true HRF. These results indicate that the amplitude of oscillations at 0.1 Hz can serve as an objective metric of the expected HRF estimation accuracy. In addition, we investigated the effect of short separation regression on the recovered HRF, and found that this improves the recovered HRF when large amplitude 0.1 Hz oscillations are present in fNIRS data. We suspect that the development of other filtering strategies may provide even further improvement.
脑血流动力学分析显示，振荡频谱范围为0.0095至2赫兹。在估计刺激诱发的血流动力学反应时，对功能近红外光谱（fNIRS）信号进行分析时，大多数这些振荡可以被滤除，但0.1赫兹左右的振荡是个例外。这是因为它们与大脑典型刺激诱发的血流动力学反应具有共同的光谱范围。在此，我们研究0.1赫兹左右的血流动力学振荡对从fNIRS数据估计血流动力学反应函数的影响。我们的结果表明，对于氧合血红蛋白浓度（HbO）中约1µM的预期反应，0.1赫兹处振幅>约1µM的迈尔波振荡会降低估计反应的准确性，与真实的血流动力学反应函数（HRF）相比，均方误差增加3倍，相关性降低（R(2)低于0.78），以此量化。这些结果表明，0.1赫兹处的振荡幅度可作为预期HRF估计准确性的客观指标。此外，我们研究了短间隔回归对恢复的HRF的影响，发现当fNIRS数据中存在大幅度0.1赫兹振荡时，这会改善恢复的HRF。我们怀疑其他滤波策略的开发可能会带来进一步的改善。
