Neuromag 306 channel data import

Lauri Parkkonen lauri at NEURO.HUT.FI
Thu Apr 27 09:43:10 CEST 2006

Dear Yisheng,

> Any one can provide a "cookbook" reference for how to import the raw
> and averaged fif files into FieldTrip?

Neuromag fif files should be directly accessible by the standard
FieldTrip functions for opening/reading MEG/EEG data files. Try first
with read_fcdc_header() to get the "meta information" and then with
read_fcdc_data() to actually read some data from the file. These
functions should work both with raw/continuous and averaged data.

NB: I just downloaded the newest daily FieldTrip release and noticed
that read_fcdc_data is unable to retrieve data when the requested span
extends over a buffer boundary. I will look into this and try to fix it.

> The Neuromag fif files don't seem to have Channel labels and their
> spatial locations embedded. What other files do we need to do source
> analysis?

The fif files are self-contained, i.e., they do include all information
necessary for the forward calculation (channel names, types, locations,
orientations, calibrations, and the MEG-device <-> head coordinate
transformation, etc.). Thus, you do not need any other files.

FieldTrip knows the geometry of the sensor coils so if you do
forward/inverse modelling in FieldTrip you should be all set.
Alternatively, if you want to code your own forward calculation routine,
you can find the coil geometries in Appendix B of the Source Modelling
Software User's Guide (a.k.a xfit), available as part of the Neuromag
analysis software distribution.

> Kimmo Uutela published a Windows version of MEG-PD (1.2.9). Is this
> version able to work with FieldTrip in Windows?

The interface (API) is the same as that of the Linux/HPUX versions so it
should work with FieldTrip, however, not all the functionality present
in the Linux version has been implemented in the Windows version as of
now. I unfortunately do not know whether FieldTrip needs the missing
bits; it should be given a try.

With the best regards,

Lauri Parkkonen
Brain Research Unit, Low Temperature Laboratory
Helsinki University of Technology
Otakaari 3 A, 02150 ESPOO, FINLAND
tel: +358-9-4512965
fax: +358-9-4512969
mailto:lauri at

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