Choosing an optimal wavelength to detect brain activity in functional near-infrared spectroscopy

Functional near-infrared spectroscopy (fNIRS) measures human brain function noninvasively. The optical response to oxy- and deoxy-hemoglobin concentration variations during brain activation is wavelength dependent because of the differing spectral shapes of the extinction coefficients of the two hemoglobin species. Choosing the optimal wavelength in fNIRS measurements is crucial to improving the performance of the technique. Here we report on a framework to estimate the spectral response to neural activation in a pre-defined local region. We found that the wavelength that exhibits the largest fractional change in the detected fluence with respect to the baseline value is around 830 nm. (C) 2021 Optical Society of America

Automated summary

fNIRS is a non-invasive method for measuring human brain function, and selecting the optimal wavelength is crucial for improving its performance. Research found that the wavelength around 830 nm exhibits the largest change in detected fluence during neural activation in a predefined local region.