Table 4.

Phase division of the vector diagram.

Phases	Conditions	Description	Modalities in which a specific phase can possibly occur
1	0 < ΔHbR < ΔHbO, ΔCOE < 0 < ΔCBV	Hyperemia dip phase with ΔHbR > 0	ISOI, fMRI, and fNIRS
2	0 < ΔHbO < ΔHbR, 0 < ΔCOE < ΔCBV		ISOI, fMRI, and fNIRS
3	ΔHbO < 0 < ΔHbR, 0 < ΔCBV < ΔCOE	Hypoxia-hyperemia dip phase with ΔCOE > 0	ISOI, fMRI, and fNIRS
4	ΔHbO < 0 < ΔHbR, ΔCBV < 0 < ΔCOE	Hypoxia-ischemia dip phase with ΔCOE > 0	fNIRS
5	ΔHbO < ΔHbR < 0, ΔCBV < 0 < ΔCOE		fNIRS
6	ΔHbR < ΔHbO < 0, ΔCBV < ΔCOE < 0	Non-dip phases with ΔCOE < 0	fNIRS
7	ΔHbR < 0 < ΔHbO, ΔCOE < ΔCBV < 0		fNIRS
8	ΔHbR < 0 < ΔHbO, ΔCOE < 0 < ΔCBV		ISOI, fMRI, and fNIRS

ISOI, intrinsic signal optical imaging; fMRI, functional magnetic resonance imaging; fNIRS, functional near-infrared spectroscopy.