Effects of distraction on pain perception: magneto- and electro-encephalographic studies

After a painful CO2 laser stimulation to the skin, the magnetoencephalography (MEG) response (164 ms in average peak latency) was not affected by distraction, but the sequential electroencephalography (EEG) responses (240-340 ms), probably generated by a summation of activities in multiple areas, were markedly affected. We suspect that the MEG response, whose dipole is estimated in the bilateral second somatosensory cortex (SII) and insula, reflects the primary activities of pain in humans.