Figure 4: (a) Serial changes of the average waveforms for oxy-Hb (red line) and deoxy-Hb (blue line) for all subjects during the PR task in the left hemisphere ROI. Standard deviations among the 12 subjects are exhibited as pale red areas. (b) Serial changes of left sensorimotor cortex activation (z-score of the oxy-Hb peak of each subject [black circle: each subject data; black line: mean value]).