[Mne_analysis] fthresh in dSPM

[Lee EDDIE]

Hi,

I am  so sorry  to  bother you again ,

I got some question these days

>From (Dale et al., 2000).qi(t) is F distributed, with three degrees of freedom for the numerator.
The degrees of freedom for the denominator is typically large, again depending
on the number of time samples used to calculate the noise covariance matrix C.

1.  in my study , my  baseline is 100 ms , so I set F(0.95,3,100)=2.69 to be my fthresh of dSPM (x=2.69) ,is that  right ?

2. I  read out my stc file in  MATLAB ,  and subtracted two condition ,then  wrote back to  stc  file

     should i use the same fthresh to show the result ? or don;t need to  set any fthresh 

because I  got some problem, if I used the same fthresh, after subtracting two condition, i didn;t see anything on dSPM

I am  so  sorry  to bother u  again  ,  hope anyone  can  help me

  Eddie


> Subject: Re: [Mne_analysis] A question which is about how to minus two	conditions in freesurfer
> From: hari at nmr.mgh.harvard.edu
> To: gramfort at nmr.mgh.harvard.edu
> CC: e7362 at hotmail.com; mne_analysis at nmr.mgh.harvard.edu
> Date: Thu, 17 Mar 2011 15:56:44 -0400
> 
> Hi,
>   mne_average_estimates (which is documented in the manual) should also
> be useful for algebraic manipulations on a set of stc files.
> 
> Regards,
> Hari
> On Thu, 2011-03-17 at 15:27 -0400, Alexandre Gramfort wrote:
> > Hi,
> > 
> > > these days , i use freesurfer and mne to  analyze my  MEG data
> > > but now , i  have a  problem as  follow :
> > > 1.how can I minus two conditions , cus I wanna see the  difference between
> > > two  conditions? EX:  (deviant condition  -  standard condition)
> > 
> > what is your setup? you want to compare within one subject? in a group
> > of subjects?
> > 
> > if it's just one subject, an easy solution consists in loading the STC
> > files for
> > both conditions in matlab, then do the difference and save the output
> > in a new stc file that you can visualize with mne_analyse. If you want to do
> > statistics that's a bit more complicated.
> > 
> > hope this helps
> > 
> > Alex
> 
> 
> 
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