Fig. 3.

Effect of tSSS cleaning of slow artifacts caused by small residual magnetized particles left from skull drilling. Spontaneous MEG data were recorded with a CTF-275 device in an epileptic patient who underwent craniotomy and a temporal resection. Top panel: Original data. MEG signals from 27 channels are displayed. Bottom panel: tSSS-cleaned data. Filters correspond to the standard CTF data acquisition system with frequency band acquired from DC to 240 Hz. No additional filtering was performed. All traces are from first-order axial gradiometers with 5 cm baseline. Reference-channel information was not applied in these data. Data courtesy of Eliane Kobayashi (McGill University, Montreal, Canada).