Influence of skin blood flow on near-infrared spectroscopy signals measured on the forehead during a verbal fluency task
Influence of skin blood flow on near-infrared spectroscopy signals measured on the forehead during a verbal fluency task
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DOI：
10.1016/j.neuroimage.2011.05.012
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发表时间：
2011-08-01
期刊：
影响因子：
5.7
通讯作者：
Kitazawa, Shigeru
中科院分区：
文献类型：
--
作者：
Takahashi, Toshimitsu;Takikawa, Yoriko;Kitazawa, Shigeru
言语流利性任务(VFT)中的大脑活动一直是许多功能成像研究的目标。大多数使用近红外光谱(NIRS)的研究报告了额叶极的主要激活，但使用PET或功能磁共振成像的研究没有。这导致我们假设，在VFT期间在前额测量的近红外信号的变化是由于皮肤血流量的变化。为了验证这一假设，我们测量了50名参与者前额的近红外信号和组织血流多普勒信号。这些测量是在每个参与者在两个60-S的时间段内说出单词时进行的，时间间隔为100 S。除了传统的30 mm(远通道)的光分离距离外，我们还使用了短距离-5 mm(近通道)-来测量完全来自表层组织的近红外信号。在两个字的产生阶段，远、近通道的氧合血红蛋白(OxHb)浓度以及多普勒血流信号以相似的方式增加：第一阶段的信号增加是第二阶段的两倍。相应地，远经络的平均血氧含量变化与近经络的变化密切相关(R(2)=0.91)，与皮肤血流信号的积分相关(R(2)=0.94)。此外，当我们通过按压覆盖一对光管的小区域来阻止皮肤血液流动时，与任务相关的近红外反应消失。此外，远通道信号的变化与多普勒信号中脉搏波的大小密切相关(R(2)=0.92)，但与脉搏频率的相关性不高(R(2)=0.43)。这些结果表明，前额氧合Hb浓度与任务相关的变化主要是由于与任务相关的皮肤血流量的变化，皮肤血流量受到不同于心率的自主神经控制。(C)2011 Elsevier Inc.保留所有权利。
Brain activity during a verbal fluency task (VFT) has been the target of many functional imaging studies. Most studies using near-infrared spectroscopy (NIRS) have reported major activation in the frontal pole, but those using PET or fMRI have not. This led us to hypothesize that changes in the NIRS signals measured in the forehead during VFT were due to changes in skin blood flow. To test this hypothesis, we measured NIRS signals and the Doppler tissue blood flow signals in the foreheads of 50 participants. The measurements were performed while each participant produced words during two 60-s periods with an interval of 100 s. In addition to a conventional optode separation distance of 30 mm (FAR channels), we used a short distance - 5 mm (NEAR channels) - to measure NIRS signals that originated exclusively from surface tissues. The oxygenated hemoglobin (oxyHb) concentration in the FAR and NEAR channels, as well as the Doppler blood flow signal, increased in a similar manner during the two periods of word production: the signal increase in the first period was twice as high as that in the second period. Accordingly, the mean changes in oxyHb concentration in the FAR channels were correlated closely with the changes in the NEAR channels (R(2) = 0.91) and with the integrated Doppler skin blood flow signal (R(2) = 0.94). Furthermore, task-related NIRS responses disappeared when we blocked skin blood flows by pressing a small area that covered a pair of optodes. Additionally, changes in the FAR channel signals were correlated closely with the magnitude of pulsatile waves in the Doppler signal (R(2) = 0.92), but these signals were not highly correlated with the pulse rate (R(2) = 0.43). These results suggest that a major part of the task-related changes in the oxyHb concentration in the forehead is due to task-related changes in the skin blood flow, which is under different autonomic control than heart rate. (C) 2011 Elsevier Inc. All rights reserved.