Sato Hiroki, Yahata Noriaki, Funane Tsukasa, Takizawa Ryu, Katura Takusige, Atsumori Hirokazu, Nishimura Yukika, Kinoshita Akihide, Kiguchi Masashi, Koizumi Hideaki, Fukuda Masato, Kasai Kiyoto
Hitachi, Ltd., Central Research Laboratory, Hatoyama, Saitama 350-0395, Japan.
Neuroimage. 2013 Dec;83:158-73. doi: 10.1016/j.neuroimage.2013.06.043. Epub 2013 Jun 21.
Near-infrared spectroscopy (NIRS) is commonly used for studying human brain function. However, several studies have shown that superficial hemodynamic changes such as skin blood flow can affect the prefrontal NIRS hemoglobin (Hb) signals. To examine the criterion-related validity of prefrontal NIRS-Hb signals, we focused on the functional signals during a working memory (WM) task and investigated their similarity with blood-oxygen-level-dependent (BOLD) signals simultaneously measured by functional magnetic resonance imaging (fMRI). We also measured the skin blood flow with a laser Doppler flowmeter (LDF) at the same time to examine the effect of superficial hemodynamic changes on the NIRS-Hb signals. Correlation analysis demonstrated that temporal changes in the prefrontal NIRS-Hb signals in the activation area were significantly correlated with the BOLD signals in the gray matter rather than those in the soft tissue or the LDF signals. While care must be taken when comparing the NIRS-Hb signal with the extracranial BOLD or LDF signals, these results suggest that the NIRS-Hb signal mainly reflects hemodynamic changes in the gray matter. Moreover, the amplitudes of the task-related responses of the NIRS-Hb signals were significantly correlated with the BOLD signals in the gray matter across participants, which means participants with a stronger NIRS-Hb response showed a stronger BOLD response. These results thus provide supportive evidence that NIRS can be used to measure hemodynamic signals originating from prefrontal cortex activation.
近红外光谱技术（NIRS）常用于研究人类大脑功能。然而，多项研究表明，诸如皮肤血流等浅表血流动力学变化会影响前额叶NIRS血红蛋白（Hb）信号。为检验前额叶NIRS-Hb信号的标准关联效度，我们聚焦于工作记忆（WM）任务期间的功能信号，并研究其与功能磁共振成像（fMRI）同时测量的血氧水平依赖（BOLD）信号的相似性。我们还同时用激光多普勒血流仪（LDF）测量皮肤血流，以检验浅表血流动力学变化对NIRS-Hb信号的影响。相关性分析表明，激活区域前额叶NIRS-Hb信号的时间变化与灰质中的BOLD信号显著相关，而非与软组织中的信号或LDF信号相关。虽然在将NIRS-Hb信号与颅外BOLD或LDF信号进行比较时必须谨慎，但这些结果表明，NIRS-Hb信号主要反映灰质中的血流动力学变化。此外，NIRS-Hb信号的任务相关反应幅度在不同参与者中与灰质中的BOLD信号显著相关，这意味着NIRS-Hb反应较强的参与者表现出较强的BOLD反应。因此，这些结果提供了支持性证据，表明NIRS可用于测量源自前额叶皮层激活的血流动力学信号。
