Figure 1.

Trial design. Listening in silence. Two opposite horizontal green (represented as light gray in the figure) arrows were presented during 4.5 s. Then, one of the arrows turned red (represented as dark gray in the figure) to indicate the side of the forth coming sound. The sound intensity was kept to zero during one of the four randomized duration delays (0, 1.5, 4.5, 7.5 s). The sound intensity then rose rapidly up to reach hearing threshold in <1 s. As soon as the subject detects the sound, he presses the response button: the sound intensity is immediately turned to zero, and the scanning begins (4 scans of 1.5 s duration were acquired successively). A resting state trial was also performed. Two opposite horizontal gray arrows instructed the subject to rest until the next color switches. The duration was 9 s for each resting state trial.