title: Characterization of the relative contributions from systemic physiological noise to whole-brain resting-state functional near-infrared spectroscopy data using single-channel independent component analysis.
abstract: Functional near-infrared spectroscopy (fNIRS) is a noninvasive neuroimaging technique used to measure changes in oxygenated hemoglobin (oxy-Hb) and deoxygenated hemoglobin (deoxy-Hb) in the brain. In this study, we present a decomposition approach based on single-channel independent component analysis (scICA) to investigate the contribution of physiological noise to fNIRS signals during rest. Single-channel ICA is an underdetermined decomposition method, which separates a single time series into components containing nonredundant spectral information. Using scICA, fNIRS signals from a total of 17 subjects were decomposed into the constituent physiological components. The percentage contribution of the classes of physiology to the fNIRS signals including low-frequency (LF) fluctuations, respiration, and cardiac oscillations was estimated using spectral domain classification methods. Our results show that LF oscillations accounted for 40% to 55% of total power of both the oxy-Hb and deoxy-Hb signals. Respiration and its harmonics accounted for 10% to 30% of the power, and cardiac pulsations and cardio-respiratory components accounted for 10% to 30%. We describe this scICA method for decomposing fNIRS signals, which unlike other approaches to spatial covariance reduction is applicable to both single- or multiple-channel fNIRS signals and discuss how this approach allows functionally distinct sources of noise with disjoint spectral support to be separated from obscuring systemic physiology.
authors.affiliation: University of Picardie Jules Verne, Faculty of Medicine, Amiens 80036, France; University Research Center (CURS), University Hospital, GRAMFC-Inserm U1105, Amiens 80054, France.
authors.forename: Ardalan
authors.initials: A
authors.lastname: Aarabi
authors.affiliation: University of Pittsburgh, Department of Radiology, 4200 Fifth Avenue, Pittsburgh, Pennsylvania 15260, United States; University of Pittsburgh, Department of Bioengineering, 4200 Fifth Avenue, Pittsburgh, Pennsylvania 15260, United States.
authors.forename: Theodore J
authors.initials: TJ
authors.lastname: Huppert
keywords: near-infrared spectroscopy; oxygenated/deoxygenated hemoglobin; physiological noise; resting state; signal decomposition; single-channel independent component analysis