Neuromagnetic data were recorded with a 148-channel whole-head magnetometer system (MAGNES TM 2500 WH, 4D Neuroimaging, San Diego, CA, USA), installed in a magnetically shielded and quiet room (Vacuumschmelze, Hanau, Germany). The recording duration was set to 5 minutes. During this period participants were laying in a comfortable supine position awake and with their eyes open. They were required to fixate on a mark on the ceiling. Furthermore, they were instructed not to move their eyes and body and to avoid engaging in any specific mental activity. To ensure compliance with the experimental requirements, their behavior was monitored with a camera installed inside the chamber.
