MEG Acquisition

Brain activity was recorded using a 306-channel whole-head MEG system (Elekta Neuromag TRIUX, Elekta Oy, Helsinki, Finland), comprising 102 magnetometers and 204 planar gradiometers, sampled at 1000 Hz with an online bandpass of 0.1-330 Hz.

Head Tracking and Stabilization

Five head-position indicator (HPI) coils tracked head position continuously throughout each session. Before each session, the participant’s head shape was digitized using a Polhemus FASTRAK system. Head stabilization was achieved with individually fitted foam casts milled from 3D head scans, filling the space between the participant’s head and the MEG helmet while still allowing natural viewing behavior. See Participants for the resulting head-repositioning precision.

Loading MEG Data

pyAVS loads raw MEG data via pyavs.load_meg_raw() (or, more commonly, through pyavs.AVSComposer – see AVSComposer Guide), which expects data in the naming/session conventions described in Dataset Structure.