Figure 3
Top-view: schematic of light sources (L1, L2, L3, and L4) and detectors (D1, D2, D3, and D4) on the sensor. The center of the sensor was positioned over position F3 according to the 10-20 system. Four channels were considered for analysis. D1-L1 were in cranial direction, D4-L4 were in caudal direction.