Neuromag 306 channel system

The first phase of Project 1 focused on basic pre-attentional (Task 1) and attentional processes (Task 2), whereas the second phase of the project focused on multisensory cognitive control (Task 4) and detection (Task 5). Task 3 was common to both phases of the project and involved a resting state fMRI scan. All fMRI/MRI data were collected on a 3.0 Tesla Siemens Trio scanner using a 12-channel head coil as described previously under the “MRI/fMRI data collection” section. MEG data were acquired for two of the tasks using an Elekta Neuromag 306 channel system as described under the “MEG data collection” section. See Table 1 for the number of SPs and HCs participating in each task. MEG task parameters are described below.

MEG data were acquired using an Elekta Neuromag 306-channel system (204 planar gradiometers, 102 magnetometers) with a sampling rate of 1000 Hz. A band-pass filter of 0.03–330 Hz was applied during acquisition. Eye movements were monitored on-line with a MEG-compatible eye-tracker (EyeLink 1000, SR Research, Ottawa, ON, Canada) recording at 500 Hz. If participants broke fixation during trials, we reminded them to refrain from moving their eyes in the next break. The electrocardiogram and the vertical and horizontal electrooculograms (EOGs) were also recorded. Head position was monitored during the experiment with emitting coils affixed to the participant's head. The positions of these coils were digitized using a Polhemus 3D tracking system (Polhemus, EastTrach 3D). The Polhemus probe was used to obtain a set of ∼100 points to record the shape of the participant's head.
Each participant completed 6 task blocks with 40 trials each. These were collected during 2–4 successive MEG recording sessions lasting approximately 25 min each, depending on the duration of breaks and reaction times of individual participants.