利用多模态光学脑成像研究前额叶静息态功能连接

多模态光学脑成像包括近红外光谱及漫射相关谱，前者探测大脑皮层的血氧代谢水平，而后者测量皮层的脑血流.皮层血氧代谢和血流是不同的两类血液动力学参量，可以从不同方面反映大脑的神经活动强度. 本研究利用多模态光学脑成像测量了人脑前额叶的静息态功能连接. 10个正常成年人参加了实验测量，分别用近红外光谱和漫射相关谱在前额叶的相同位置记录了大脑8分钟的自发波动信号，测量覆盖区域包括左侧额下皮层及左背外侧前额叶. 低频段血氧代谢信号（包括含氧血红蛋白、脱氧血红蛋白及总血红蛋白浓度）用来揭示基于血氧信号的静息态功能连接，而相同频段的脑血流信号用来确定基于脑血流的静息态功能连接. 两类血液动力学参量的静息态功能连接均揭示:背外侧前额叶区域内的连接大于背外侧前额叶与额下皮层之间的区域间连接，显示相邻的背外侧前额叶和额下皮层是不同的功能区域. 此外定量比较基于两类血液动力学参量的功能连接发现，基于血氧代谢的连接有更大的连接强度，表明在同一个功能区内，静息时血氧代谢信号的时间同步性更高.

Using Multimodal Optical Brain Imaging to Investigate Resting-State Functional Connectivity in Frontal Cortex

Multimodal optical brain imaging consists of near infrared spectroscopy (NIRS) and diffuse correlation spectroscopy (DCS). NIRS probes blood oxygenation level in cortex, while DCS measures cerebral blood flow. Blood oxygenation level and cerebral blood flow are two different classes of hemodynamic variables, each reflecting different aspect on the neural activity in the brain. In the present study, the multimodal optical imaging was used to investigate resting-state functional connectivity (RSFC) in the frontal cortex. 10 normal adults participated in the experiment in which 8 minutes of spontaneous activity of brain was separately recorded by NIRS and DCS. The measured area included left inferior frontal cortex (IFC) and left dorsolateral prefrontal cortex (DLPFC). Low frequency component of blood oxygenation signal (i.e., oxygenated hemoglobin, deoxygenated hemoglobin and total hemoglobin) was used to reveal oxygenation-based RSFC, while the cerebral blood flow signal in the same frequency range was used to identify cerebral blood flow-based RSFC. Both blood oxygenation-based and cerebral blood flow-based RSFC showed that the intra-regional connectivity within DLPFC was stronger than the inter-regional connectivity between DLPFC and IFC, implying that DLPFC and IFC, each belongs to a distinct functional area, though they are anatomically adjacent. Quantitative comparison between RSFC revealed by the two classes of hemodynamic variables showed the oxygenation-based RSFC was stronger than the cerebral blood flow-based RSFC, indicating the blood oxygenation in a functional area was more synchronized in time than the cerebral blood in resting-state.