摘要
与传统的核磁共振、脑电图等脑功能成像方法相比,功能性近红外光谱(fNIRS)技术具有抗电磁干扰和可直接检测血氧代谢信号等优势。本团队基于锁相光子计数技术发展了一套面向脑机接口(BCI)应用的便携式fNIRS拓扑成像系统,并开展了一系列仿体和在体实验,以评估该系统的性能。具体来说,仿体实验结果表明该系统具有良好的稳定性、线性度和抗串扰能力。在体实验采用了屏息和心算两种刺激范式,系统以4Hz的采样频率进行同步测量,结果表明,该系统可以准确跟踪全局兴奋(屏息刺激)和局部兴奋(心算刺激)的时间变化曲线。本团队进一步对心算刺激下的测量结果进行了光学拓扑成像,结果显示,此刺激的兴奋区域大致位于前额叶左半部中央位置。此外,本系统进行了充分的小型化设计,可以应用于医疗、日常等情境。这一系统可以实现高灵敏度、全并行的微弱兴奋信号检测,为fNIRS-BCI的临床应用提供了一种实用、高效的测量手段。
Objective Functional near-infrared spectroscopy (fNIRS)is an effective neuroimaging tool used to directly determine changes in oxygenated hemoglobin (HbO)and deoxygenated hemoglobin (HbR).This technique offers portable and radiation-free alternatives to conventional neuroimaging modalities,such as functional magnetic resonance imaging,positron emission tomography,and electroencephalograph.However,current portable fNIRS systems have limited detection sensitivity due to the employment of photodiodes working in analog mode.To cope with the adversities,we propose a portable two-wavelength continuous-wave fNIRS-topography system based on lock-in photon-counting technology to be applied in cognitive neuroscience and brain-computer interface (BCI)studies in a daily environment.The proposed system has a good prospect of application in faint activation detection by integrating the parallel measurement capability derived from lock-in technology and the high sensitivity derived from photon-counting technology.Thus,the proposed system should provide a noninvasive route,reasonable temporal resolution,and high-sensitive information for studying fNIRS-BCI.Methods In this study,the proposed portable fNIRS system possesses four pairs of source-and detection-optodes,which are matched with the configurations of a nonoverlapping source-detector array to conduct experiments.Source-optode bundles two single-mode fibers with a core diameter of 9μm connected to two laser diodes(LDs)at785and 830nm wavelengths.Besides,a modulator with eight square wave signals of different frequencies is designed based on a field-programmable gate array(FPGA)kit.The modulated light reaches the cerebral cortex and is subject to refraction,scattering,and absorption by HbO and HbR.A part of the light is redirected to the scalp,where HbO and HbR concentration changes are detected by the detection module in turn,which adopts a photomultiplier tube with a linear range of 5.0×106 s-1 and a dark count of 600s-1 as the core device.A lock-in photon-counting demod
作者
刘洋
刘东远
张耀
白璐
高峰
Liu Yang;Liu Dongyuan;Zhang Yao;Bai Lu;Gao Feng(College of Precision Instruments and Optoelectronics Engineering,Tianjin University,Tianjin 300072,China;Tianjin Key Laboratory of Biomedical Detecting Techniques and Instruments,Tianjin University,Tianjin 300072,China)
出处
《中国激光》
EI
CAS
CSCD
北大核心
2021年第11期143-151,共9页
Chinese Journal of Lasers
基金
国家自然科学基金(61575140)。
关键词
医用光学
功能性近红外光谱
脑机接口技术
高灵敏度
在体实验
光学拓扑成像
medical optics
functional near-infrared spectroscopy
brain-computer interface
high sensitivity
in-vivo experiment
optical topography
