Resting state recordings from the OMEGA database

Authors: Francois Tadel, Guiomar Niso, Elizabeth Bock.

This tutorials introduces how to download a resting state recordings from the OMEGA database, and how to process them into Brainstorm.

License

The Open MEG Archive (OMEGA) is the fruit of a collaborative effort by the McConnell Brain Imaging Centre and the Université de Montréal to build a centralised repository in which to regroup MEG data for open dissemination. This continuously expanding repository also contains anatomical MRI volumes, demographic and questionnaire information, and eventually will feature other forms of electrophysiological data (e.g. EEG, field, and cell recordings). OMEGA features the technological framework for multi-centric data aggregation, and is amongst the largest freely available resting-state MEG datasets presently available.

You are free to use all data in OMEGA for research purposes; however, we ask that you please cite the following reference in your publications if you have used data from OMEGA:

Niso G, Rogers C, Moreau JT, Chen LY, Madjar C, Das S, Bock E, Tadel F, Evans A, Jolicoeur P, Baillet S
OMEGA: The Open MEG Archive, Neuroimage, 2015

Presentation of the experiment

Experiment

• 5 subjects
• 5 minute resting sessions, eyes open

MEG acquisition

• Acquisition at 2400Hz, with a CTF 275 MEG system,

• Recorded at the Montreal Neurological Institute in 2015-2016.
• Anti-aliasing low-pass filter at 600Hz, files saved with the CTF 3rd order gradient compensation.
• Recorded channels (340):
  • 1 Stim channel indicating the presentation times of the audio stimuli: UPPT001 (#1)
  • 1 Audio signal sent to the subject: UADC001 (#316)
  • 1 Response channel recordings the finger taps in response to the deviants: UDIO001 (#2)
  • 26 MEG reference sensors (#5-#30)
  • 274 MEG axial gradiometers (#31-#304)
  • 2 EEG electrodes: Cz, Pz (#305 and #306)
  • 1 ECG bipolar (#307)
  • 2 EOG bipolar (vertical #308, horizontal #309)
  • 12 Head tracking channels: Nasion XYZ, Left XYZ, Right XYZ, Error N/L/R (#317-#328)
  • 20 Unused channels (#3, #4, #310-#315, #329-340)

• The data in this dataset has been formatted along the BIDS specifications (Brain Imaging Data Structure, http://bids.neuroimaging.io)

Head shape and fiducial points

• 3D digitization using a Polhemus Fastrak device driven by Brainstorm. The .pos files contain:
  • The position of the center of CTF coils

  • The position of the anatomical references we use in Brainstorm: Nasion and connections tragus/helix, as illustrated here

  • Around 150 head points distributed on the hard parts of the head (no soft tissues)

Subject anatomy

• Structural T1 image recorded with a 1.5T MRI

• Processed with FreeSurfer 5.3

Download and installation

First, make sure you have enough space on your hard drive, at least 350Gb:

• Raw files: 100Gb

• Processed files: 250Gb

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