Figure 2.

An example of the changes in oxy-hemoglobin (O₂Hb) and deoxy-hemoglobin (HHb) in right and left frontal regions during BK117 flight. The dotted arrow indicates the flight situation. The solid arrow indicates a call by the pilot. The outline arrow indicates the downward head movement of the pilot (bold: 2~3 seconds, thin: 1~2 seconds).