Georgetown University Medical Center, Center for Functional and Molecular Imaging, Washington, DC 20057, USA.
J Biomed Opt. 2010 Nov-Dec;15(6):061702. doi: 10.1117/1.3505007.
Near-infrared spectroscopy is a novel imaging technique potentially sensitive to both brain hemodynamics (slow signal) and neuronal activity (fast optical signal, FOS). The big challenge of measuring FOS noninvasively lies in the presumably low signal-to-noise ratio. Thus, detectability of the FOS has been controversially discussed. We present reliable detection of FOS from 11 individuals concurrently with electroencephalogram (EEG) during a Go-NoGo task. Probes were placed bilaterally over prefrontal cortex. Independent component analysis (ICA) was used for artifact removal. Correlation coefficient in the best correlated FOS-EEG ICA pairs was highly significant (p < 10(-8)), and event-related optical signal (EROS) was found in all subjects. Several EROS components were similar to the event-related potential (ERP) components. The most robust "optical N200" at t = 225 ms coincided with the N200 ERP; both signals showed significant difference between targets and nontargets, and their timing correlated with subject's reaction time. Correlation between FOS and EEG even in single trials provides further evidence that at least some FOS components "reflect" electrical brain processes directly. The data provide evidence for the early involvement of prefrontal cortex in rapid object recognition. EROS is highly localized and can provide cost-effective imaging tools for cortical mapping of cognitive processes.
近红外光谱是一种新型的成像技术，可能对脑血流动力学（慢信号）和神经元活动（快速光学信号，FOS）都敏感。无创测量 FOS 的最大挑战在于信号噪声比可能较低。因此，FOS 的可检测性一直存在争议。我们在 11 个人进行 Go-NoGo 任务的同时，使用脑电图（EEG）可靠地检测到 FOS。探头放置在前额皮质的双侧。使用独立成分分析（ICA）去除伪影。最佳相关 FOS-EEG ICA 对的相关系数具有高度显著性（p < 10(-8))，并且在所有受试者中都发现了事件相关光学信号（EROS）。几个 EROS 成分与事件相关电位（ERP）成分相似。最稳健的“光学 N200”在 t = 225 ms 时与 N200 ERP 重合；这两种信号在目标和非目标之间均显示出显著差异，并且它们的时间与受试者的反应时间相关。即使在单次试验中，FOS 和 EEG 之间的相关性也进一步证明了至少一些 FOS 成分“直接反映”了大脑的电过程。该数据为前额叶皮层在快速物体识别中的早期参与提供了证据。EROS 高度本地化，可为认知过程的皮质映射提供具有成本效益的成像工具。
