Table 1.

NIRS-mediated BCI studies utilizing motor imagery signals.

Reference	Brain area	Features	Classification accuracy (%)
NIRS-based system
Coyle et al.50	Motor cortex	HbO value	75
Coyle et al.51	Motor cortex	HbO value	70 to 90
Sitaram et al.52	Bil motor cortex	Mean of $\mathrm{\Delta }\mathrm{HbO}$ and HbR	89.1
Holper and Wolf53	Secondary motor cortex	HbO signals (mean, variance, skewness, and kurtosis)	81
Naseer and Hong54	Bil motor cortex	HbO signals (mean and slope of $\mathrm{\Delta }\mathrm{HbO}$)	87.2
Hong et al.55	Motor cortex and PFC	HbO signals (mean and slope of $\mathrm{\Delta }\mathrm{HbO}$)	75.7 (three class: right/left/arithmetic)
EEG-NIRS hybrid system
Fazli et al.56	Bil motor cortex	NIRS: mean of $\mathrm{\Delta }\mathrm{HbO}$ and HbR EEG: power	83.1
Koo et al.57	Bil motor cortex	NIRS: $\mathrm{\Delta }\mathrm{HbO}$ EEG: power and variance	88 (self-paced)
Yin et al.58	Bil motor cortex	NIRS: signals from HbR, HbO, HbT, HbO-HbR, light absorption (two wavelengths) EEG: power, instantaneous phase, instantaneous amplitude, and instantaneous frequency	89
Buccino et al.59	Bil motor cortex	NIRS: mean and slope of $\mathrm{\Delta }\mathrm{HbO}$ and HbR EEG: power and variance	72.2 (right/left)

Note: PFC, prefrontal cortex; HbO, oxygenated hemoglobin; HbR, deoxygenated hemoglobin; and HbT, total hemoglobin.