Fig. 2.

Optode arrangements for fNIRS in 3D space. Eight transmitter optodes and two receiver optodes were configured to form a total of eight measurement channels. As highlighted by the red double-headed arrows, channels in the right hemisphere included Channel 1 (S1–R1), Channel 2 (S2–R1), Channel 3 (S3–R1), and Channel 4 (S4–R1); channels in the left hemisphere included Channel 5 (S5–R2), Channel 6 (S6–R2), Channel 7 (S7–R2), and Channel 8 (S8–R2). All optodes were positioned over the prefrontal cortex according to the International 10–20 EEG coordinate system