This study compares the hemodynamic signals measured by near-infrared spectroscopy (NIRS) and functional magnetic resonance imaging (fMRI) in both temporal and spatial domains across multiple cognitive tasks. NIRS offers advantages such as finer temporal resolution and ease of administration but has lower spatial resolution and signal-to-noise ratio (SNR) compared to fMRI. The researchers scanned participants simultaneously with NIRS and fMRI on four cognitive tasks: finger tapping, go/no-go, judgment of line orientation, and an N-back working memory task. They found that while NIRS signals have significantly lower SNR, they are often highly correlated with fMRI measurements. The correlation strength was influenced by factors such as the distance between the scalp and the brain, and the distance between the photon path's emitter and detector. In the spatial domain, an elliptical path between the emitter and detector was found to correlate most strongly with the BOLD response. The study concludes that NIRS can be a useful substitute for fMRI in studying brain activity related to cognitive tasks, provided that the spatial resolution is adequate and the lower SNR is accounted for.This study compares the hemodynamic signals measured by near-infrared spectroscopy (NIRS) and functional magnetic resonance imaging (fMRI) in both temporal and spatial domains across multiple cognitive tasks. NIRS offers advantages such as finer temporal resolution and ease of administration but has lower spatial resolution and signal-to-noise ratio (SNR) compared to fMRI. The researchers scanned participants simultaneously with NIRS and fMRI on four cognitive tasks: finger tapping, go/no-go, judgment of line orientation, and an N-back working memory task. They found that while NIRS signals have significantly lower SNR, they are often highly correlated with fMRI measurements. The correlation strength was influenced by factors such as the distance between the scalp and the brain, and the distance between the photon path's emitter and detector. In the spatial domain, an elliptical path between the emitter and detector was found to correlate most strongly with the BOLD response. The study concludes that NIRS can be a useful substitute for fMRI in studying brain activity related to cognitive tasks, provided that the spatial resolution is adequate and the lower SNR is accounted for.