 |
 |
Dear Vladimir Thank you for your reply, I will redo the analysis with the con.images. I tried already on one subject and the results appear pretty much the same. Will have to confirm. 1 more questions: 1) After 2nd level analysis, I assume that voxels that survived FWER correction are those that are significantly activated in one condition but not the other. So, if I plot based on coordinate of the global max, doesn't the attached figure tell me about source power modulation as a function of time? And the shaded area represents desynchronization? Thank you for your help. Tommy On Thu, Sep 15, 2011 at 7:51 PM, Vladimir Litvak <[log in to unmask]>wrote: > Dear Tommy, > > It's the first one. > > Best, > > Vladimir > > > > On 15 Sep 2011, at 01:41, Tommy Ng <[log in to unmask]> wrote: > > Hi Vladimir > > I input a .mat file into fieldtrip LCMV beamformer and the output was in a > separate folder "tstatBF_images". In this folder, there are 2 .nii files, 1) > normdiff_pow_ , 2) tstat_pow. Where is the contrast image that beamformer > output? > > Thanks. > > Tommy > > > > On Thu, Sep 15, 2011 at 4:59 AM, Johannes Gehrig < <[log in to unmask]> > [log in to unmask]> wrote: > >> Dear Valdimir and SPM list, >> >> your reply confused me a little bit. Why isn't he supposed to take t-stat >> images to the 2nd level? Is this in general not the right way? I perform >> beamforming of my conditions aggainst baseline and perform a paired t-test >> with the t-stat images on the second level. My results are comparable to a >> fMRI study with the same paradigm. >> >> Very curious about your reply! >> >> Best, >> Johannes >> >> -----Ursprüngliche Nachricht----- >> Von: "Vladimir Litvak" < <[log in to unmask]> >> [log in to unmask]> >> Gesendet: 14.09.2011 11:08:47 >> An: <[log in to unmask]>[log in to unmask] >> Betreff: Re: [SPM] 1st level contrast_MEG/EEG >> >> >Dear Tommy, >> > >> >You sound a little bit confused. First you are not supposed to take >> >t-stat images to the second level, but contrast images that beamfomer >> >also gives you. Second, you cannot extract time series from these >> >images as they are already averaged over time. So I'm not sure what it >> >is you are plotting, but these are not time series. Third, the 1st >> >level button in SPM M/EEG has absolutely nothing to do with this as it >> >is only used for averaging within sensor-level scap x time images. >> > >> >You can extract time series from given coordinates in individual >> >subjects by using the 'beamformer source extraction' functionality in >> >the beamforming toolbox. >> > >> >Best, >> > >> >Vladimir >> > >> >On Wed, Sep 14, 2011 at 4:53 AM, Tommy Ng < <[log in to unmask]> >> [log in to unmask]> wrote: >> >> Hi SPM experts >> >> This is a summary of my MEG analysis: >> >> 1) Beamforming analysis on 15 subjects with 2 conditions. >> >> 2) Output: 15 t-stats images for each condition. 30 images in total. >> >> 3) Take these images to 2nd level analysis >> >> 4) SPM spits out coordinate of global maxima in left BA4 >> >> 5) Using the 'plot' function, I extract time-series of left BA 4 (see >> >> attached) >> >> >> >> Now, I am hoping to use this coordinate to extract activity in that >> voxel >> >> from individual subject. I tried doing 1st level analysis, that is, >> contrast >> >> the t-stats images of each subject, which theoretically should produce >> a >> >> SPM.mat file but I got this error: >> >> ??? Error using ==> spm_eeg_firstlevel at 83 >> >> The window is out of limits for image >> >> >> /Volumes/MY_PASSPORT/Exp#2_2/109_PS/-100to0_tstatBf_images/normdiff_pow_cefspm8_2010_08_25_0109_ME033_B1-thinout_15-30Hz.nii,1 >> >> ??? Error while evaluating uicontrol Callback >> >> Can anyone tell me whether this is a viable option to obtain 1st level >> >> SPM.mat for individual subject so that stats can be done for all >> subjects, >> >> or provide an alternative solution? >> >> Thank you in advance. >> >> Tommy Ng >> >> >> ___________________________________________________________ >> Schon gehört? WEB.DE hat einen genialen Phishing-Filter in die >> Toolbar eingebaut! <http://produkte.web.de/go/toolbar> >> http://produkte.web.de/go/toolbar >> > >