Dear Haiteng,
2009/4/17 hiten <[log in to unmask]>:
> Dear SPMers:
> Now I use spm8 to process MEG data .After projection to 2D- or a 3D-space
> (source reconstruction), the data is in voxel-space and ready to be
This phrase is not completely clear to me. You either did a 3D source
reconstruction and then your images are always 3D or you exported
sensor-level data to images and then you can get 2D, but that's
exactly what 1st level is for.
> analysed.But there is only some informaiton in spm5 manual (chapter 15), not
> in spm8 yet.Procedures illustrated in spm5 has been changed in spm8
> especially at 1st level.I am confused and don't know what to do next.Could
> anyone give me more information about MEG/EEG modelling and statistic in
> spm8? Thanks in advance!
Depending on what exactly you are doing the answer is as follows:
1) If you did 3D source reconstruction i.e. your images look like the
MNI brain, you shouldn't use the 1st level button. You can set up a
contrast using 2nd level button and this works exactly the same as 2nd
level analysis in fMRI so you can rely on the relevant part of the
manual. It also worked exactly the same way in SPM5 (except for the
new SPM8 GUI for the job manager).
If you indeed used the source reconstruction what comes below is not
relevant for you.
2) If you have 3D images from the sensor level (i.e. with two spatial
dimensions and one time dimension) and you want to do statistics in
space-time, you should also go directly to 2nd level button and again
it works exactly like for fMRI.
3) Finally the only thing that 1st level button does is averages
within a space-time image from (2) to get a 2D image representing
space only. For instance you know that your effect of interest appears
between 100 and 200 ms and the only thing you want to know is where it
is on the scalp and whether it's significant or not. Then you just
average your images between 100 and 200 ms to get 2D scalp maps
(using 1st level button) and then use the 2nd level button to do
statistics on those scalp maps.
I hope this helps.
Vladimir
> --
> haiteng jiang
> Research Center for Learning Science,
> Southeast University
> Si Pai Lou 2 # , Nanjing, 210096, P.R.China
> Brain Imaging Lab
> Mobile:+86-13813998827
> Email:[log in to unmask]
>
>
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