Abstract
To improve the spatial resolution of imaging and get more effective brain function information, a multi-distance probe configuration with three distances (28.2, 40, and 44.7 mm) and 52 channels is designed. At the same time, a data conversion method of modified Beer–Lambert law (MBLL) with partial pathlength (PPL) is proposed. In the experiment, three kinds of tasks, grip of left hand, grip of right hand, and rest, are performed with eight healthy subjects. First, with a typical single-distance probe configuration (30 mm, 24 channels), the feasibility of the proposed MBLL with PPL is preliminarily validated. Further, the characteristic of the proposed method is evaluated with the multi-distance probe configuration. Compared with MBLL with differential pathlength factor (DPF), the proposed MBLL with PPL is able to acquire more obvious concentration change and can achieve higher classification accuracy of the three tasks. Then, with the proposed method, the performance of the multi-distance probe configuration is discussed. Results show that, compared with a single distance, the combination of the three distances has better spatial resolution and could explore more accurate brain activation information. Besides, the classification accuracy of the three tasks obtained with the combination of three distances is higher than that of any combination of two distances. Also, with the combination of the three distances, the two-class classification between different tasks is carried out. Both theory and experimental results demonstrate that, using multi-distance probe configuration and the MBLL with PPL method, the performance of brain function detected by NIRS can be improved.
Highlights
Functional near-infrared spectroscopy is a widely used non-invasive functional neuroimaging technology (Sato et al, 2016)
There are 24 sources and 42 detectors in total, and more than 100 channels can be created by the combination of those sources and detectors
The first, second, and third rows represent the task of LG, right hand (RG), and RE, respectively
Summary
Functional near-infrared spectroscopy (fNIRS) is a widely used non-invasive functional neuroimaging technology (Sato et al, 2016). FNIRS is a safe, low-noise, portable, easyto-use, and low-cost technique (Naseer and Hong, 2015). It has a higher spatial resolution than electroencephalogram and has a better temporal resolution than functional magnetic resonance imaging (fMRI). FNIRS device measures the intensity of light after passing through a certain brain. The measured light intensity could be converted to the change of oxygenated hemoglobin (HbO) and deoxygenated hemoglobin (HbR) concentrations with some algorithms, and further the activation state of this area can be determined. Brain– computer interfaces based on fNIRS and the clinical application of fNIRS both have significant growths (Naseer and Hong, 2013; Khan et al, 2014, 2018; Naseer et al, 2014; Hong et al, 2015; Naseer and Hong, 2015)
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