Cui, Bray, Reiss (2010) Functional near infrared spectroscopy (NIRS) signal improvement based on negative correlation between oxygenated and deoxygenated hemoglobin dynamics NeuroImage 49(4) 3039-46


Near infrared spectroscopy (NIRS) is a promising technology for functional brain imaging which measures hemodynamic signals from the cortex, similar to functional magnetic resonance imaging (fMRI), but does not require the participant to lie motionless in a confined space. NIRS can therefore be used for more naturalistic experiments, including face to face communication, or natural body movements, and is well suited for real-time applications that may require lengthy training. However, improving signal quality and reducing noise, especially noise induced by head motion, is challenging, particularly for real time applications. Here we study the properties of head motion induced noise, and find that motion noise causes the measured oxygenated and deoxygenated hemoglobin signals, which are typically strongly negatively correlated, to become more positively correlated. Next, we develop a method to reduce noise based on the principle that the concentration changes of oxygenated and deoxygenated hemoglobin should be negatively correlated. We show that despite its simplicity, this method is effective in reducing noise and improving signal quality, for both online and offline noise reduction. Copyright 2009 Elsevier Inc. All rights reserved.

近红外光谱(NIRS)是功能性脑成像的有前途的技术,其测量来自皮质的血流动力学信号,类似于功能磁共振成像(fMRI),但不要求参与者在密闭空间中静止。 NIRS因此可以用于更自然的实验,包括面对面交流或自然身体运动,并且非常适合可能需要长时间训练的实时应用。然而,改善信号质量和降低噪声,特别是由头部运动引起的噪声是具有挑战性的,特别是对于实时应用。在这里,我们研究头部运动诱导噪声的属性,发现运动噪声导致测量的氧合和脱氧血红蛋白信号,通常强烈负相关,变得更正相关。接下来,我们开发了一种基于氧合和脱氧血红蛋白的浓度变化应该负相关的原理减少噪声的方法。我们表明,尽管它的简单,这种方法是有效的减少噪声和提高信号质量,在线和离线降噪。