These 2D locations are created by projecting 3D locations represented
in head coordinates so the differences you find are due to different
head positions of your subjects in the helmet. This is by design, but
you also can load a standard channel template file for all your
On Mon, Feb 28, 2011 at 10:55 PM, Erick Britis Ortiz
<[log in to unmask]> wrote:
> Thank you as always for the prompt response!
> For you to know at least what I am talking about, a picture is attached
> with the projected MEG sensors (colored by region) in my 22 subjects.
> Left is greenish, right is reddish.
> The problem is that I see no reason for the MEG sensors not to have
> simply a standard position. In the Fieldtrip plots, they have (for
> example, in CTF151.lay). I will follow your advice, no matter. But this
> is a bit dangerous in the general case, don't you think? As I said, I
> just do not know if it is by design, else I could "fix" it.
> On 2011-02-28 23:28, Vladimir Litvak wrote:
>> Hi Erick,
>> SPM uses the same algorithm as Fieldtrip to generate a layout from the
>> sensor array so it should be quite similar, just the convention for
>> representing it is slightly different. I don't know what exactly the
>> problem is so it's hard for me to advise you. In principle you can use
>> the GUI functionality in Prepare or your own script to generate any
>> layout you like and then load it as a channel template file via
>> Prepare (this is a mat-file, there is an example for CTF in
>> On Mon, Feb 28, 2011 at 10:22 PM, Erick Britis Ortiz
>> <[log in to unmask]> wrote:
>>> Hi Vladimir,
>>> I have been using spm_eeg_convert2images to transform my MEG frequency
>>> analysis results to image volumes and run statistics. The objective
>>> being to determine lateralization in language (in children) by frequency.
>>> I assumed that spm_eeg_convert2scalp would use a standard 2D layout (à
>>> la Fieldtrip), and when I checked, this is not true. This makes
>>> lateralization studies, for instance, much more difficult, and I could
>>> think of others. What is the advantage?
>>> My guess was that setting D.channels.X_plot2D and Y_plot2D to empty
>>> would generate a default arrangement, but this also did not work. Could
>>> you shed some light at the issue?