Figure 3.

Single subject: For each subject, superimposition of S1a (solid line), S1b (dotted line), and M1 (dashed line) sources averaged by centring on the median nerve stimulation (t = 0, vertical solid line) in the time window [−30, 100] ms. For reference, 20 and 30 ms are indicated (vertical dotted lines). Mean across subjects: The three source signals averaged on nerve stimuli are reported separately, as well as the superimposed ones (bottom). It clearly results that the S1a source reacts maximally at around 20 ms, S1b at around 30 ms, and M1 less than S1a and S1b, but with higher reaction at 30 ms than at 20 ms. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]