You sound quite confused indeed. Perhaps you should take a look at the
SPM EEG paper again (http://www.hindawi.com/journals/cin/2011/852961/)
particularly the parts about sensor-level statistics (Section 3,
Figure 2) and section 4.6. "Convert to images" menu has to do with
sensor-level statistics and what you are trying to do is source-level.
Analyze (.img + .hdr) and NIFTI (.nii) formats are very similar and
are used interchangeably in SPM. Either can be used for statistics. It
so happens that the sensor-level images are created in Analyze format
and source-level images in NIFTI. So the bottom line is, use source
images such as the one you sent me for statistics. You don't need to
do anything else.
Regarding the time dimension, SPM does not support statistics for more
than 3 dimensions so it would not be possible to further analyze
images with both 3D space in time. You can only do analysis on both
time and space only at the sensor level because scalp maps can be
reduced to 2D. So you must summarize the time and frequency dimensions
as explained in the paper. If you want to look at multiple time
windows you can generate multiple images at the same time, but the
time windows will be at least ~8ms.
On Wed, Jul 20, 2011 at 1:23 PM, Urs Bachofner <[log in to unmask]> wrote:
> Hi Vladimir,
> sorry to bother you again with an amateur's question but I would appreciate
> it if you could point me into the right direction.
> I'm still working with my EEG Files (induced) that are now converted into
> Nifti Files (by clicking the Image button in the Source Reconstruction
> menu). However I now read that for statistics you should choose "Convert to
> Images" in the drop down menu and after I did this to the .mat file I didnt
> get one Nifti File but two files for every good trial, a .hdr and a .img.
> Which of the files (the .nii or the .hdr/.img pair) am I supposed to use for
> statistical analysis?
> If I should use the .hdr/.img files, how can I get SPM to produce one
> averaged pair (induced) instead a pair for all good trials?
> If I should use the .nii file: Why is there no time scale in the image as I
> display it? I have trials of 600ms and would like to see the activation in
> each time point?
> (There is one nifti Image in the attachment)
> Thanks a lot for every bit of help
> NEU: FreePhone - 0ct/min Handyspartarif mit Geld-zurück-Garantie!
> Jetzt informieren: http://www.gmx.net/de/go/freephone