title: Concurrent fNIRS-fMRI measurement to validate a method for separating deep and shallow fNIRS signals by using multidistance optodes.
abstract: It has been reported that a functional near-infrared spectroscopy (fNIRS) signal can be contaminated by extracerebral contributions. Many algorithms using multidistance separations to address this issue have been proposed, but their spatial separation performance has rarely been validated with simultaneous measurements of fNIRS and functional magnetic resonance imaging (fMRI). We previously proposed a method for discriminating between deep and shallow contributions in fNIRS signals, referred to as the multidistance independent component analysis (MD-ICA) method. In this study, to validate the MD-ICA method from the spatial aspect, multidistance fNIRS, fMRI, and laser-Doppler-flowmetry signals were simultaneously obtained for 12 healthy adult males during three tasks. The fNIRS signal was separated into deep and shallow signals by using the MD-ICA method, and the correlation between the waveforms of the separated fNIRS signals and the gray matter blood oxygenation level-dependent signals was analyzed. A three-way analysis of variance ([Formula: see text]) indicated that the main effect of fNIRS signal depth on the correlation is significant [[Formula: see text], [Formula: see text]]. This result indicates that the MD-ICA method successfully separates fNIRS signals into spatially deep and shallow signals, and the accuracy and reliability of the fNIRS signal will be improved with the method.
authors.affiliation: Hitachi, Ltd. , Central Research Laboratory, Hatoyama, Saitama 350-0395, Japan.
authors.forename: Tsukasa
authors.initials: T
authors.lastname: Funane
authors.affiliation: Hitachi, Ltd. , Central Research Laboratory, Hatoyama, Saitama 350-0395, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Sato
authors.affiliation: The University of Tokyo , Graduate School of Medicine, Department of Youth Mental Health, Bunkyo-ku, Tokyo 113-8655, Japan.
authors.forename: Noriaki
authors.initials: N
authors.lastname: Yahata
authors.affiliation: The University of Tokyo , Graduate School of Medicine, Department of Neuropsychiatry, Bunkyo-ku, Tokyo 113-8655, Japan ; King's College London , Institute of Psychiatry, MRC Social, Genetic and Developmental Psychiatry Centre, London, SE5 8AF, United Kingdom.
authors.forename: Ryu
authors.initials: R
authors.lastname: Takizawa
authors.affiliation: The University of Tokyo , Graduate School of Medicine, Department of Neuropsychiatry, Bunkyo-ku, Tokyo 113-8655, Japan.
authors.forename: Yukika
authors.initials: Y
authors.lastname: Nishimura
authors.affiliation: The University of Tokyo , Graduate School of Medicine, Department of Neuropsychiatry, Bunkyo-ku, Tokyo 113-8655, Japan.
authors.forename: Akihide
authors.initials: A
authors.lastname: Kinoshita
authors.affiliation: Hitachi, Ltd. , Central Research Laboratory, Hatoyama, Saitama 350-0395, Japan.
authors.forename: Takusige
authors.initials: T
authors.lastname: Katura
authors.affiliation: Hitachi, Ltd. , Central Research Laboratory, Hatoyama, Saitama 350-0395, Japan.
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Atsumori
authors.affiliation: Gunma University Graduate School of Medicine , Department of Psychiatry and Neuroscience, Maebashi, Gunma 371-8511, Japan.
authors.forename: Masato
authors.initials: M
authors.lastname: Fukuda
authors.affiliation: The University of Tokyo , Graduate School of Medicine, Department of Neuropsychiatry, Bunkyo-ku, Tokyo 113-8655, Japan.
authors.forename: Kiyoto
authors.initials: K
authors.lastname: Kasai
authors.affiliation: Hitachi, Ltd. , Central Research Laboratory, Hatoyama, Saitama 350-0395, Japan.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Koizumi
authors.affiliation: Hitachi, Ltd. , Central Research Laboratory, Hatoyama, Saitama 350-0395, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Kiguchi
keywords: finger tapping; functional magnetic resonance imaging; functional near-infrared spectroscopy; laser Doppler flowmetry; verbal-fluency task; working memory