OPM Data recorded from the Functional Imaging Lab (FIL), Department of Imaging Neuroscience, University College London
Dataset provided courtesey of George O'Neill
sub-noise_ses-001_task-noise220622_run-001 - 5 second empty room recording from 22nd June 2022. Included is the output from a FieldTrip-like importer for the same data (as the _fieldTrip.mat file).
The data is organised in a BIDS-eque format listed below.
data_folder
│
├───[FILE_PREFIX]_meg.bin [REQUIRED] [FIL specific]
├───[FILE_PREFIX]_meg.json [REQUIRED]
├───[FILE_PREFIX]_channels.tsv [REQUIRED]
├───[FILE_PREFIX]_positions.tsv [OPTIONAL] [FIL specific]
└───[FILE_PREFIX]_coordsystem.json [OPTIONAL]
However, distinct to BIDS we store no duplicate metadata within our _meg.bin file, all necessary metadata is provided within the BIDS-mandated supplementary files, sensor positions/orientations in _positions.tsv
The _meg.bin contains the raw sensor-level data. There are no header bytes. Data is stored by default in single-precision IEEE big-endian binary format. However, some older (pre Sept 2019) public datasets may be double precision.
Data is ordered in as
| Bytes | Channel | Timepoint |
|---|---|---|
| 0-3 | 0 | 0 |
| 4-7 | 1 | 0 |
| 8-11 | 2 | 0 |
| 12-15 | 3 | 0 |
| 16-19 | 0 | 1 |
| 20-23 | 1 | 1 |
| 24-27 | 2 | 1 |
| 28-31 | 3 | 1 |
| 32-35 | 0 | 2 |
etc.
Tab-separated value format file to describe the sensor positions and orientations, columns are as follows:
- name: Channel name, must match name contained in
_channels.tsv. - Px: Position, x-coordinate.
- Py: Position, y-coordinate.
- Pz: Position, z-coordinate.
- Ox: Orientation, x-component.
- Oy: Orientation, y-component.
- Oz: Orientation, z-component.
Note 1: The ordering of the channels in _positions.tsv does not need to match the ordering of _channels.tsv. Not all sensors in the dataset may have a positions.
Note 2: If using _coordsystem.json to list fiducial locations, please ensure the fields in HeadCoilCoordinates are in the same space as the sensors.