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Importing data

Turn a real recording file into a ready dataset: signal, electrode locations and events.

4 lessons: 3 core, 1 recommended

After this station you can:

  • Import an EDF, BDF or BrainVision file
  • Attach channel locations and check them on a head plot
  • Confirm events arrived with the right types and timing

Lessons

  1. Importing raw files: EDF, BDF & BrainVisionCore15 min
  2. Channel locationsCore12 min
  3. EventsCore12 min
  4. BIDS & OpenNeuro dataRecommended15 min

Test yourself

4 questions. Your score stays with you and isn't sent anywhere.

1. You have the file S001R03.edf from PhysioNet. Which menu do you import it with?
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The correct answer: File > Import data > Using EEGLAB functions and plugins > From EDF/EDF+/GDF files (BIOSIG toolbox)

EDF, EDF+ and GDF files are read by the Biosig plugin, with the function pop_biosig. Load existing dataset opens .set files only, and the other two menus are for BrainVision and Neuroscan formats.

Review the lesson: Importing raw files: EDF, BDF & BrainVision

2. Which statements about importing different formats are true? (Select all that apply)
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The correct answer: A BioSemi BDF file is read with Biosig, and you should pick a temporary reference channel at import, For a BrainVision recording you pick the .vhdr file, not .eeg or .vmrk, If you untick Import EDF+ annotations, the event count may drop to zero

A Neuroscan .cnt and an ANT .cnt are two different formats with the same extension, so choose the plugin by the system, not the extension. BioSemi data are recorded reference-free and lose much of their signal quality if left without a reference.

Review the lesson: Importing raw files: EDF, BDF & BrainVision

3. An event's latency in EEG.event is 673, and the sampling rate is 160 Hz. How many seconds after the start of the recording did it happen?
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The correct answer: 4.2 seconds

Latency in EEG.event is in samples. Time in seconds = (sample number − 1) ÷ sampling rate = (673 − 1) ÷ 160 = 4.2 seconds. We subtract 1 because the first sample is number 1 and sits at time zero.

Review the lesson: Events

4. Put the steps for working on S001R03.edf in the order of station 2:
  1. Look up the channel locations in the standard template
  2. Check the event types and counts with eeg_eventtypes
  3. Import the file with the Biosig plugin
  4. Remove the dots from the channel names
  5. Save a .set copy after import
Show the answer

The correct answer: 1. Import the file with the Biosig plugin, 2. Save a .set copy after import, 3. Remove the dots from the channel names, 4. Look up the channel locations in the standard template, 5. Check the event types and counts with eeg_eventtypes

You import first, then save a .set so you do not repeat the import. Then you fix the names, because the location lookup matches names with the template, and Cz.. does not match Cz. Then you check the events before any later epoching.

Review the lesson: Events