Figure 2.

Experimental designs of the tasks. A, One example trial of the mental calculation task. The horizontal addition problem was displayed up to 10 s, and disappeared once the SPACE key was pressed. B, Example trials of the 2-back task. For each trial, a white square in a 3 × 3 black grid was displayed for 500 ms, with an interstimulus interval of 2500 ms. C, Block design for the fMRI. In each block, a 40 s task condition was presented, followed by a 14 s fixation slide.