BCIwiki (bciwiki.com) — Differences in signal quality partly explain why task-evoked functional near-infrared spectroscopy (fNIRS) responses vary between individuals, researchers reported in a preprint posted to bioRxiv on September 1, 2026, alongside a large, open, multi-task, near whole-head fNIRS dataset. The work is listed by Maastricht University and has not been peer reviewed.
Fifty-seven participants completed resting-state, motor action, motor imagery, emotion recognition, visual and auditory tasks during fNIRS recording. The team also captured pulse oximetry, heart rate, blood oxygen saturation, respiration, room temperature, galvanic skin response, electrocardiogram and electromyography, plus short-channel recordings.
Signal quality was assessed with 4 metrics: the scalp coupling index (SCI), coefficient of variation (CV), signal-to-noise ratio (SNR) and a spectral measure the authors call the coupling SNR (cSNR). The metrics were weakly to moderately correlated, except SNR and CV, which showed the expected inverse relationship. All metrics were significantly related to channel length and associated with task-related activation estimates, and group-level analyses confirmed activation in expected regions.
The authors say the metrics capture complementary features of fNIRS signal quality, and that the dataset can support future evaluation of physiological correction and confound mitigation methods. DOI: 10.64898/2026.06.06.728412.