Functional near infrared spectroscopy (fNIRS) is a noninvasive optics-based neuroimaging modality successfully applied to real-life settings. The technology uses light in the near infrared range (650-950nm) to track changes in oxygenated (HbO2) and deoxygenated hemoglobin (Hb) obtained from measured light intensity using light-tissue interaction principles. fNIRS data processing involves artifact removal and hemodynamic signal conversion using modified Beer-Lambert law (MBLL) to obtain Hb and HbO2, reliably. fNIRS signals can get contaminated by various noise sources of physiological and non-physiological origins. Various algorithms have been proposed for the elimination of artifacts from frequency selective filters to blind source separation methods. Hemodynamic signal extraction using raw intensity measurements at multiple wavelengths based on MBLL usually involves apriori knowledge of certain conversion parameters such as molar extinction coefficients (ε) and differential path length factor (DPF). Different sets of conversion parameters dependent upon wavelength, chromophores, and age have been reported. Variation in processing algorithms and parameters can cause differences in Hb and HbO2 extraction which can in turn change study outcomes. Using fNIRS, we have previously shown significant increases in oxygenation in the prefrontal cortex from Single-Task-Walking (STW) to Dual-task-Walking (DTW) conditions in older adults due to greater cognitive demands inherent in the latter condition. In the current study, we re-analyzed our data and determined that although using different conversion parameters i.e. ε and age dependent DPF and filter cut-off frequencies at 0.14 and 0.08Hz including those designed to remove confounding effects of Mayer waves had caused some linear increases or decreases on the extracted Hb and HbO2 signals, those effects were minimal to none in task related comparisons and hence, the overall study outcomes.

中文翻译：

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处理方法对老年人主动行走任务中评估的fNIRS信号的影响。

功能性近红外光谱（fNIRS）是一种基于无创光学的神经影像技术，已成功应用于现实生活中。该技术使用近红外范围（650-950nm）的光来跟踪根据光组织相互作用原理从测量的光强度获得的氧合（HbO2）和脱氧血红蛋白（Hb）的变化。fNIRS数据处理涉及使用修正的比尔-朗伯定律（MBLL）去除伪迹和进行血流动力学信号转换，从而可靠地获得Hb和HbO2。fNIRS信号可能会被生理和非生理起源的各种噪声源污染。已经提出了各种算法来消除从频率选择滤波器到盲源分离方法的伪像。使用基于MBLL的多个波长的原始强度测量值进行血流动力学信号提取通常需要先验了解某些转换参数，例如摩尔消光系数（ε）和微分路径长度因子（DPF）。已经报道了取决于波长，发色团和寿命的不同组的转化参数。处理算法和参数的变化会导致Hb和HbO2提取的差异，进而改变研究结果。使用fNIRS，我们先前已显示老年人的前额叶皮层中的氧合显着增加，从单任务步行（STW）到双任务步行（DTW）状况，是由于后者固有的认知需求增加。在目前的研究中