title: Noise reduction in functional near-infrared spectroscopy signals by independent component analysis.
abstract: Functional near-infrared spectroscopy (fNIRS) is used to detect concentration changes of oxy-hemoglobin and deoxy-hemoglobin in the human brain. The main difficulty entailed in the analysis of fNIRS signals is the fact that the hemodynamic response to a specific neuronal activation is contaminated by physiological and instrument noises, motion artifacts, and other interferences. This paper proposes independent component analysis (ICA) as a means of identifying the original hemodynamic response in the presence of noises. The original hemodynamic response was reconstructed using the primary independent component (IC) and other, less-weighting-coefficient ICs. In order to generate experimental brain stimuli, arithmetic tasks were administered to eight volunteer subjects. The t-value of the reconstructed hemodynamic response was improved by using the ICs found in the measured data. The best t-value out of 16 low-pass-filtered signals was 37, and that of the reconstructed one was 51. Also, the average t-value of the eight subjects' reconstructed signals was 40, whereas that of all of their low-pass-filtered signals was only 20. Overall, the results showed the applicability of the ICA-based method to noise-contamination reduction in brain mapping.
authors.affiliation: Department of Cogno-Mechatronics Engineering, Pusan National University, 30 Jangjeon-dong, Geumjeong-gu, Busan 609-735, South Korea.
authors.forename: Hendrik
authors.initials: H
authors.lastname: Santosa
authors.forename: Melissa Jiyoun
authors.initials: MJ
authors.lastname: Hong
authors.forename: Sung-Phil
authors.initials: SP
authors.lastname: Kim
authors.forename: Keum-Shik
authors.initials: KS
authors.lastname: Hong
mesh_terms: D000328:Adult; D006439:Hemodynamics; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D010100:Oxygen / Q000378:metabolism; D017397:Prefrontal Cortex / Q000378:metabolism / Q000502:physiology; D012815:Signal Processing, Computer-Assisted; D059629:Signal-To-Noise Ratio; D013055:Spectrophotometry, Infrared / Q000379:methods*; D013223:Statistics as Topic
chemical_list: D010100:Oxygen