Investigate the Frequency Spectrum of Noise Signals Affecting Synchronous Signals of fMRI and fNIRS in Resting and Moving Wrists

Abstract

Purpose: The nerve signals are often contaminated by the non-nerve signals in the same frequency range, i.e. low frequencies in the range of 0.1 Hz. Among the different medical imaging tools, Functional Magnetic Resonance Imaging (fMRI) has been widely used by scientists and scholars due to its high spatial resolution for brain mapping. Materials and Methods: Also, the use of Functional Near-Infrared Spectroscopy (NFIRS) has continued to rise and regarding its high temporal resolution, it is considered as the complement of FMRI. Results: However, the effect of non-nerve functions is observed in both methods. Specially, by showing that non-nervous Low Frequency Oscillations (LFOs) 1) are merely non-nervous, because they can be measured by the environmental NIRS; 2) their internal origin is close to the heart; 3) in comparison with the available LF models based on respiration and the merely non-nervous changes in heart, they are unique in their spatial and temporal features, it seems that the systemic signals are moving through the cerebral arteries. Conclusion: In this paper, LF Oscillations (LFOs) are compared with simultaneous NIRS/FMRI. Also, we discuss the non-neurological effects during simple motions of the wrist in FMRI showing that a significant portion of them, especially in motion state networks, are non-nerve and we measure the sensitivity of NIRS to non-neural LFOs through mapping of nerve and non-nerve LFOs with an extra high spatial and temporal resolution.