source projection

Sanja Kovacevic sanja at UNM.EDU
Fri Aug 19 19:42:21 CEST 2005

Hi Robert,

I've tried using megrealign and megplanar with the CTF 275
ch data, however I run into problems with source
projection. First, for megrealign there was a warning
about the higher order synthetic gradiometer
configuration. Nevertheless, megrealign ran, but after
freqanalysis the resulting tfr values for several channels
were much higher (3 orders of magnitude) than for the rest
of the channels (which was not the case for the original
not realigned data). Second, megplanar stopped running
with "the forward model does not look like EEG, nor like
MEG" error. I've saved the CTF data with the 3rd order
noise cancellation on (via newDs -filter) and then read
these noise canceled data into fieldtrip. However, I've
only read in MEG and STIM channels, I haven't read in the
reference channels. Do you have any thoughts on what might
be going on?

I appreciate your help,


On Fri, 12 Aug 2005 14:02:20 +0200
  Robert Oostenveld <r.oostenveld at FCDONDERS.RU.NL> wrote:
> Hi Sanja,
> On 11-aug-2005, at 22:52, Sanja Kovacevic wrote:
>> I am trying to use
>>meginterpolate/freqanalysis/combineplanar to get
>> the tfr
>> data in the planar gradiometer system, instead of the
>>original 275
>> ch axial.
>> However, combineplanar needs planarchannelset, but this
>>function is
>> not
>> included in the 20050811 distribution. Could you include
>> function in
>> the next distribution?
> Please find the function attached to this mail. I will
>add it to the  next daily releases, sorry that it was
> The attached version however does not include the 275ch
>CTF system  yet, but it is easy to add. You basically
>only have to make a table  with the planar channel labels
>that should be combined, and the name  of the combined
>channel (i.e. the original name). I would appreciate  it
>if you would send me the table information for the CTF
>275 system,  I will then update the release version as
>> I have a set of questions related to meginterpolate: Can
>> be used
>> for ploting the planar data? Should I use a default
>>single sphere
>> model for
>> each subject or a single sphere model particular for a
>>subject for
>> realignment? Should "nominal" sensor locations be used
>>as a
>> template for
>> each subject, or do you recommend taking an average
>>across subjects
>> for the
>> template?
> Yes, but only for combineplanar'ed data in combination
>with  topoplotTFR. It is conceptually not possible to
>make a topography of  the "raw" planar data itself, but
>you can do a multiplotER and  multiplotTFR of the planar
>data. However, that would require another  lay file. The
>NM122all.lay file is one for the Neuromag system that
> plots the 122 planar channels at 66 locations, with
>horizontal and  vertical channel next to each other.
> If you do not specify a layout in the cfg of
>multiplotTFR, the  private subfunction createlayout will
>construct a layout on the fly  based on the gradiometer
>positions. Usually the plotting is more  controlled with
>a manually eddited layout file, but the automatic one
> can serve as starting point. Looking into the code, I
>now realise  that there still are some loose ends. The
>megplanar function does not  return the planar gadiometer
>definition. Please have a look at the  private functions
>axial2planar and createlayout, and use them  together to
>construct a planar layout file.
> best regards,
> Robert

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