Fig. 1.

Median-nerve oddball paradigm. Block 1: 15% of the stimuli were delivered to the right wrist and 85% to the left wrist. Subjects were instructed to count silently the rare stimuli to the right wrist. Block 2: the rare and frequent stimuli were reversed, and subjects were instructed to silently count the rare stimuli to the left wrist. For each side, oddball MEG signals were obtained by subtracting the frequent responses from the rare responses across different blocks as indicated by the arrows. Block 3 was identical to Block 1, and Block 4 was identical to Block 2