change in data structures, inside, dimord, foi and toi

Robert Oostenveld r.oostenveld at FCDONDERS.RU.NL
Fri Feb 24 18:09:14 CET 2006

Dear FieldTrip users

We have made two relatively large changes to FieldTrip that may lead
to incompatibilities with your own scripts, therefore a word of warning:

The changes affect the "home/common" version inside the Donders
Centre from this moment on.

The changes affect the daily released ftp version from version
20060224, i.e. today onward. That version does not exist yet, but
will be uploaded to the ftp version this evening (CET). From today
onward, a daily release will be made available again (which was not
the case for the last 2 weeks).

The first change is that of volumes. Previously source volumes could
have an "inside" and an "outside" vector with indices, indicating the
voxels that were scanned with the beamformer or not. Those two
"inside" and "outside" vectors have been replaced by an locigal/
boolean "inside" volume, which is 1 if the voxel was inside the brain
(i.e. beamed) and 0 if outside the brain (i.e. not beamed).

The second change relates to the dimord field that most fieldtrip
data structures have, and the freq.foi and freq.toi fields. The use
of the dimord field has been made consistent between all functions,
due to which some dimords had to be renamed. More importantly, the
time and frequency axis in the output of the freqanalysis function
have been renamed to freq.time (used to be freq.toi) and freq.freq
(used to be freq.foi). This ensures that the dimord and the
description of the axes in the data structure is consistent. The
dimord also will specify "chan_freq_time" instead of
"sgncmb_frq_tim", i.e. the dimord is in better correspondence with
the data strucute.

We have kept all FieldTrip functions backward compatible, i.e. old
datastructures that you have previously computed and saved to disk in
a mat file will still work with the new FieldTrip functions. Since
the changes affected many fieldtrip functions, it could very well be
that the changes introduced some bugs here and there. Please inform
us about them, so that we can fix them.

Sorry about the inconvenience that this may cause with respect to
your analysis scripts. The change was required to ensure a further
consistent development of the FieldTrip code.

yours sincerely,

Robert Oostenveld, PhD
F.C. Donders Centre for Cognitive Neuroimaging
Radboud University Nijmegen
phone: +31-24-3619695

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